[分享]新手和CN必看

----------------------------------------------------------
ArcTan 三角函数
----------------------------------------------------------
范例
Cos
var R: Extended;
begin
R := Cos(Pi);
end;
----------------------------------------------------------
Sin
----------------------------------------------------------
范例
var
R: Extended;
S: string;
begin
R := Sin(Pi);
Str(R:5:3, S);
Canvas.TextOut(10, 10, 'The Sin of Pi is ' + S);
end;
----------------------------------------------------------
Unit System
函数原型 function ArcTan(X: Extended): Extended;
函数原型 function Cos(X: Extended): Extended;
函数原型 function Sin(X: Extended): Extended;
----------------------------------------------------------
说明 X为径度.
Tan(x) === Sin(x) / Cos(x)
ArcSin(x) = ArcTan (x/sqrt (1-sqr (x)))
ArcCos(x) = ArcTan (sqrt (1-sqr (x)) /x)
左边这三个不是函数,而是右边运算求得.
范例
var
R: Extended;
begin
R := ArcTan(Pi);
end;
范例 var
R: Extended;
S: string;
begin
R := Sin(Pi);
Str(R:5:3, S);
Canvas.TextOut(10, 10, 'The Sin of Pi is ' + S);
end;
----------------------------------------------------------
Frac 求一个实数的小数部份
----------------------------------------------------------
Unit System
函数原型 function Frac(X: Real): Real;
说明 X为实数.
范例 var
R: Real;
begin
R := Frac(123.456); { 0.456 }
R := Frac(-123.456); { -0.456 }
end;
------------------------------------------
Int 求一个实数的整数部份
------------------------------------------
Unit System
函数原型 function Int(X: Real): Real;
说明 X为实数.
范例 var
R: Real;
begin
R := Int(123.456); { 123.0 }
R := Int(-123.456); { -123.0 }
end;
------------------------------------------
Pi 就是数学的Pi
------------------------------------------
Unit System
函数原型 function Pi: Extended;
说明 它是一个函数,但我们就把它当作是预设的变数来用吧!
Pi= 3.1415926535897932385
------------------------------------------
Sqr X的平方
-----------------------------------------
范例
var
S, Temp: string;
begin
Str(Sqr(5.0):3:1, Temp);
S := '5 squared is ' + Temp + #13#10;
Str(Sqrt(2.0):5:4, Temp);
S := S + 'The square root of 2 is ' + Temp;
MessageDlg(S, mtInformation, [mbOk], 0);
end;

------------------------------------------
Date and time routines 日期及时间函数
------------------------------------------
Date 传回目前的日期

Unit SysUtils
函数原型 function Date: TDateTime;
范例 procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := 'Today is ' + DateToStr(Date);
end;
------------------------------------------
DateTimeToStr 日期时间转换成内定型字串(1996/12/20 09:12:20 PM)
------------------------------------------
Unit SysUtils
函数原型 function DateTimeToStr(DateTime: TDateTime): string;
范例 procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := DateTimeToStr(Now);
end;
--------------------------------------------------------
DateTimeToString 日期时间转换成自定型字串
-------------------------------------------------------
Unit SysUtils
函数原型 procedure DateTimeToString(var Result: string; const Format:
string; DateTime: TDateTime);
范例 procedure TForm1.FormCreate(Sender: TObject);
var
s:string;
begin
DateTimeToString(s,'dddd,mmmm d,yyyy "at" hh:mm
AM/PM',Now);
Label1.Caption :=s;
end;
结果 星期五,十二月 20,1996 at 09:20 PM
-----------------------------------------------------------------------------
**** Format格式叁考下面.FormatDateTime.
--------------------------------------------------------
DateToStr 日期转换成内定型字串.(1996/12/20)
--------------------------------------------------------
Unit SysUtils
函数原型 function DateToStr(Date: TDateTime): string;
范例
procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := 'Today is ' + DateToStr(Date);
end;
# Date, DateToStr Example
--------------------------------------------------------
DayOfWeek 求叁数日期是星期几.
--------------------------------------------------------
Unit SysUtils
函数原型 function DayOfWeek(Date: TDateTime): Integer;
说明 传回值是一整数,1~7.
星期日为1.
范例
procedure TForm1.Button1Click(Sender: TObject);
var
ADate: TDateTime;
days: array[1..7] of string;
begin
days[1] := 'Sunday';
days[2] := 'Monday';
days[3] := 'Tuesday';
days[4] := 'Wednesday';
days[5] := 'Thursday';
days[6] := 'Friday';
days[7] := 'Saturday';
ADate := StrToDate(Edit1.Text);
ShowMessage(Edit1.Text + ' is a ' + days[DayOfWeek(ADate)];
end;
# StrToDate, DayOfWeek Example
--------------------------------------------------------
DecodeDate 将TDateTime型态的日期变数，转为Word型态.
--------------------------------------------------------
范例
procedure TForm1.Button1Click(Sender: TObject);
var
Present: TDateTime;
Year, Month, Day, Hour, Min, Sec, MSec: Word;
begin
Present:= Now;
DecodeDate(Present, Year, Month, Day);
Label1.Caption := 'Today is Day ' + IntToStr(Day) + ' of Month '
+ IntToStr(Month) + ' of Year ' + IntToStr(Year);
DecodeTime(Present, Hour, Min, Sec, MSec);
Label2.Caption := 'The time is Minute ' + IntToStr(Min) + ' of Hour '
+ IntToStr(Hour);
end;
# DecodeDate, DecodeTime Example

范例
procedure TForm1.Button1Click(Sender: TObject);
var
MyTime: TDateTime;
begin
MyTime := EncodeTime(0, 45, 45, 7);
Label1.Caption := TimeToStr(MyTime);
end;
--------------------------------------------------------
FormatDateTime 将日期时间依Format的格式转换给一字串.
--------------------------------------------------------
Unit SysUtils
函数原型 function FormatDateTime(const Format: string; DateTime:
TDateTime): string;
**** 类似DateTimeToString.
Format格式
c 内定值ShortDateFormat的格式.(1996/12/20 09:20:15 PM).
d 日期,前面不补0.(1-31)
dd 日期,前面补0.(01-31)
ddd 星期.(星期日).
Dddd 中文2.01版,同上.
ddddd 日期.(1996/12/20)
dddddd 日期.(1996年12月20日)
m 月份,前面不补0.(1-12)
mm 月份,前面补0.(01-12)
mmm 中文显示.(十二月)
mmmm 中文2.01版,同上.
Yy 年度.(00-99)
yyyy 年度.(0000-9999)
h 小时.(0-23)
hh 小时.(00-23)
n 分钟.(0-59)
nn 分钟.(00-59)
s 秒钟.(0-59)
ss 秒钟.(00-59)
t 时间.(09:20 PM)
tt 时间.(09:20:15 PM)
am/pm 单独显示am or pm.(若大写,则显示大写)
a/p 单独显示a or p.
范例
The following example assigns 'The meeting is on Wednesday, February 15, 1995 at 10:30 AM' to the string variable S.
S := FormatDateTime('"The meeting is on " dddd, mmmm d, yyyy, " at " hh:mm AM/PM',
StrToDateTime('2/15/95 10:30am'));//???

--------------------------------------------------------
StrToDateTime 将字串转为TDateTime型态的日期时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function StrToDateTime(const S: string): TDateTime;

范例
procedure TForm1.Button1Click(Sender: TObject);
var
ADateAndTime: TDateTime;
begin
ADateAndTime := StrToDateTime(Edit1.Text);
Table1.FieldByName('TimeStamp').AsDateTime := ADateAndTime;
end;
--------------------------------------------------------
StrToTime 将字串转为TDateTime型态的时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function StrToTime(const S: string): TDateTime;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
ATime: TDateTime;
begin
ATime := StrToTime(Edit1.Text);
if ATime < 0.50 then
ShowMessage('Good Morning')
else
ShowMessage('Good Afternoon');
end;
--------------------------------------------------------
Time 传回目前的时间.
--------------------------------------------------------
Unit SysUtils
函数原型 function Time: TDateTime;
范例
procedure TForm1.Timer1Timer(Sender: TObject);
var
DateTime : TDateTime;
str : string;
begin
DateTime := Time; // store the current date and time
str := TimeToStr(DateTime); // convert the time into a string
Caption := str; // display the time on the form's caption
{ Note This could have been done with the following line of code:
Caption := TimeToStr(Time); }
end;
# Time, TimeToStr Example

--------------------------------------------------------
GetMem 配置指位器P的记忆体空间，大小可自行设定.

--------------------------------------------------------
范例
var
F: file;
Size: Integer;
Buffer: PChar;
begin
AssignFile(F, 'test.txt');
Reset(F, 1);
try
Size := FileSize(F);
GetMem(Buffer, Size);
try
BlockRead(F, Buffer^, Size);
ProcessFile(Buffer, Size);
finally
FreeMem(Buffer);
end;
finally
CloseFile(F);
end;
end;
--------------------------------------------------------
FreeMem 释放GetMem所配置的记忆体.
--------------------------------------------------------
Unit System
函数原型 procedure GetMem(var P: Pointer; Size: Integer);
函数原型 procedure FreeMem(var P: Pointer[; Size: Integer]);
范例 var
F: file;
Size: Integer;
Buffer: PChar;
begin
AssignFile(F, 'test.txt');
Reset(F, 1);
try
Size := FileSize(F);
GetMem(Buffer, Size);
try
BlockRead(F, Buffer^, Size);
ProcessFile(Buffer, Size);
finally
FreeMem(Buffer);
end;
finally
CloseFile(F);
end;
end;

--------------------------------------------------------
ExpandFileName 将档案名称加在目前所在之路径全名之後
--------------------------------------------------------
Unit SysUtils
函数原型 function ExpandFileName(const FileName: string): string;
说明 设目前目录为 c:\windows 档案名称为 abc.txt
则结果为 c:\windows\abc.txt
**** 此函数并不是求abc.txt的所在路径.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
begin
S:=ExpandFileName('abc.txt');
Label1.Caption:=S;
end;
范例
procedure TForm1.Button1Click(Sender: TObject)
begin
ListBox1.Items.Add(ExpandFileName(Edit1.Text));
end;

------------------------------------------------------------------
DirectoryExists 目录是否存在------------------------------------------------------------------
Unit
FileCtrl

uses FileCtrl;

procedure TForm1.Button1Click(Sender: TObject);
begin
if not DirectoryExists('c:\temp') then
if not CreateDir('C:\temp') then
raise Exception.Create('Cannot create c:\temp');
end;
--------------------------------------------------------
ForceDirectories 目录
---------------------------------------------------------
Unit FileCtrl
函数原型 function ForceDirectories(Dir: string): Boolean;

procedure TForm1.Button1Click(Sender: TObject);
var
Dir: string;
begin
Dir := 'C:\APPS\SALES\LOCAL';
if DirectoryExists(Dir) then
Label1.Caption := Dir + ' was created'
end;

--------------------------------------------------------
ExtractFilePath 分析字串中的路径
--------------------------------------------------------
Unit SysUtils
函数原型 function ExtractFilePath(const FileName: string): string;
说明 设S字串为 c:\windows\abc.txt
则结果为 c:\windows范例 procedure TForm1.Button1Click(Sender: TObject);
var
S: String;
P1:String;
begin
P1:='c:\windows\abc.txt';
S:=ExtractFilePath(P1);
Label1.Caption:=S;
end;
范例
begin
with Session do
begin
ConfigMode := cmSession;

try
AddStandardAlias('TEMPDB', ExtractFilePath(ParamStr(0)), 'PARADOX');
finally
ConfigMode := cmAll;
end;
end;
##ConfigMode, AddStandardAlias, ExtractFilePath example
--------------------------------------------------------
FileSearch 寻找档案在磁碟机中的正确路径
--------------------------------------------------------
Unit SysUtils
函数原型 function FileSearch(const Name, DirList: string): string;
范例 var
s:string;
begin
s:= FileSearch('abc.txt', 'c:\window\');
Label1.Caption:=s;
end;
说明 找到传回c:\window\abc.txt 找不到传回空字串.
范例
procedure TForm1.Button1Click(Sender: TObject);
var
buffer: array [0..255] of char;
FileToFind: string;
begin
GetWindowsDirectory(buffer, SizeOf(buffer));
FileToFind := FileSearch(Edit1.Text, GetCurrentDir + ';' + buffer);
if FileToFind = ' then
ShowMessage('Couldn't find ' + Edit1.Text + '.')
else
ShowMessage('Found ' + FileToFind + '.');
end;
##FileSearch, ShowMessage Example

-----------------------------------------------------------------------------
FileSetDate 设定档案的日期及时间(DOS型态).
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileSetDate(Handle: Integer; Age: Integer): Integer;
说明 传回值为0表示成功.
-----------------------------------------------------------------------------
DeleteFile 删除档案
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function DeleteFile(const FileName: string): Boolean;
范例 一 DeleteFile('DELETE.ME');

范例 二 if FileExists(FileName) then
if MessageDlg('Do you really want to delete ' +
ExtractFileName(FileName) + '?'), []) = IDYes then
DeleteFile(FileName);
##FileExists, DeleteFile Example
-----------------------------------------------------------------------------
RenameFile 更改档名
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function RenameFile(const OldName, NewName: string):Boolean;
范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do

begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
-----------------------------------------------------------------------------
DiskFree 磁碟机剩馀空间(Bytes)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function DiskFree(Drive: Byte): Integer;
范例 var
S: string;
begin
S := IntToStr(DiskFree(0) div 1024) + ' Kbytes free.';
Label1.Caption:=S;
end;
说明 Drive
0=目前磁碟机,1=A磁碟机,2=B磁碟机...传回值若为-1,表示磁碟机侦测错误.
范例
var
S: string;
AmtFree: Int64;
Total: Int64;
begin
AmtFree := DiskFree(0);
Total := DiskSize(0);
S := IntToStr(AmtFree div Total) + 'percent of the space on drive 0 is free: ' (AmtFree div 1024) + ' Kbytes free. ';
Canvas.TextOut(10, 10, S);
end;
##DiskFree, DiskSize Example

-----------------------------------------------------------------------------
FileCreate 建档
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileCreate(const FileName: string): Integer;

范例
procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;

FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then

raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin

for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;

end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
-----------------------------------------------------------------------------
FileClose 关档
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 procedure FileClose(Handle: Integer);
范例

procedure TForm1.Button1Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X: Integer;
Y: Integer;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
FileWrite(FileHandle,
StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
FileWrite(FileHandle,
StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
for X := 0 to StringGrid1.ColCount ? 1 do
begin
for Y := 0 to StringGrid1.RowCount ? 1 do
begin
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, StringLen, SizeOf(StringLen));
FileWrite(FileHandle,
StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
end;
end;
FileClose(FileHandle);
end;
end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example

============================================
**** 它是以Handle为叁数.
============================================
FileRead 读取档案
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FileRead(Handle: Integer; var Buffer; Count: Integer):Integer;
范例
procedure TForm1.Button1Click(Sender: TObject);

var
iFileHandle: Integer;
iFileLength: Integer;
iBytesRead: Integer;
Buffer: PChar;
i: Integer
begin
if OpenDialog1.Execute then
begin
try
iFileHandle := FileOpen(OpenDialog1.FileName, fmOpenRead);
iFileLength := FileSeek(iFileHandle,0,2);
FileSeek(iFileHandle,0,0);
Buffer := PChar(AllocMem(iFileLength + 1));
iBytesRead = FileRead(iFileHandle, Buffer, iFileLength);
FileClose(iFileHandle);
for i := 0 to iBytesRead-1 do
begin
StringGrid1.RowCount := StringGrid1.RowCount + 1;
StringGrid1.Cells[1,i+1] := Buffer[i];
StringGrid1.Cells[2,i+1] := IntToStr(Integer(Buffer[i]));
end;
finally
FreeMem(Buffer);
end;
end;
end;
##FileOpen, FileSeek, FileRead Example

-----------------------------------------------------------------------------
FindClose 结束FindFirst/FindNext
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);

var
sr: TSearchRec;
FileAttrs: Integer;
begin
StringGrid1.RowCount := 1;
if CheckBox1.Checked then
FileAttrs := faReadOnly
else
FileAttrs := 0;
if CheckBox2.Checked then
FileAttrs := FileAttrs + faHidden;
if CheckBox3.Checked then
FileAttrs := FileAttrs + faSysFile;
if CheckBox4.Checked then
FileAttrs := FileAttrs + faVolumeID;
if CheckBox5.Checked then

FileAttrs := FileAttrs + faDirectory;
if CheckBox6.Checked then
FileAttrs := FileAttrs + faArchive;
if CheckBox7.Checked then

FileAttrs := FileAttrs + faAnyFile;

if FindFirst(Edit1.Text, FileAttrs, sr) = 0 then

begin
with StringGrid1 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin

Cells[1,RowCount-1] := sr.Name;
Cells[2,RowCount-1] := IntToStr(sr.Size);
end;
while FindNext(sr) = 0 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
RowCount := RowCount + 1;
Cells[1, RowCount-1] := sr.Name;

Cells[2, RowCount-1] := IntToStr(sr.Size);
end;
end;
FindClose(sr);
end;
end;
end;
##FindFirst, FindNext, FindClose Example
-----------------------------------------------------------------------------
FindFirst 寻找第一个符合的档案.
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);

var
sr: TSearchRec;
FileAttrs: Integer;
begin
StringGrid1.RowCount := 1;
if CheckBox1.Checked then
FileAttrs := faReadOnly
else
FileAttrs := 0;
if CheckBox2.Checked then
FileAttrs := FileAttrs + faHidden;
if CheckBox3.Checked then
FileAttrs := FileAttrs + faSysFile;
if CheckBox4.Checked then
FileAttrs := FileAttrs + faVolumeID;
if CheckBox5.Checked then

FileAttrs := FileAttrs + faDirectory;
if CheckBox6.Checked then
FileAttrs := FileAttrs + faArchive;
if CheckBox7.Checked then

FileAttrs := FileAttrs + faAnyFile;

if FindFirst(Edit1.Text, FileAttrs, sr) = 0 then

begin
with StringGrid1 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
Cells[1,RowCount-1] := sr.Name;
Cells[2,RowCount-1] := IntToStr(sr.Size);
end;
while FindNext(sr) = 0 do
begin
if (sr.Attr and FileAttrs) = sr.Attr then
begin
RowCount := RowCount + 1;
Cells[1, RowCount-1] := sr.Name;
Cells[2, RowCount-1] := IntToStr(sr.Size);
end;
end;
FindClose(sr);
end;
end;
end;
##FindFirst, FindNext, FindClose Example

-----------------------------------------------------------------------------
FloatToTextFmt 将浮点数转换为格式化十进位.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FloatToTextFmt(Buffer: PChar; const Value;
ValueType: TFloatValue; Format: PChar): Integer;
-----------------------------------------------------------------------------
FormatFloat 将浮点数转换为格式化字串.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function FormatFloat(const Format: string; Value: Extended):
string;
-----------------------------------------------------------------------------
StrToFloat 将字串转换为浮点数.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrToFloat(const S: string): Extended;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
Value:Double;
S:String;
begin
S:=' 1234.56 ';
Value:=StrToFloat(S);
Label1.Caption:=Format('转换为 [%9.3f]',[Value]);
end;

注意 若S字串含有非数字字元,会产生错误讯号.
-----------------------------------------------------------------------------
TextToFloat 将 null-terminated 字串转换为浮点数.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function TextToFloat(Buffer: PChar; var Value; ValueType:
TFloatValue): Boolean;

===========================================
Flow-control routines 流程控制常式
===========================================
Break 从 for, while, or repeat 终止跳出.
-----------------------------------------------------------------------------
Unit System

函数原型 procedure Break;
范例 var
S: string;
begin
while True do
begin
ReadLn(S);
try
if S = ' then Break;
WriteLn(S);
finally
{ do something for all cases }
end;
end;
end;
-----------------------------------------------------------------------------
Continue 从 for, while, or repeat 继续执行.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Continue;
范例 var
F: File;
i: integer;
begin
for i := 0 to (FileListBox1.Items.Count - 1) do
begin
try
if FileListBox1.Selected[i] then
begin
if not FileExists(FileListBox1.Items.Strings[i]) then
begin
MessageDlg('File: ' +FileListBox1.Items.Strings[i]
+ ' not found', mtError, [mbOk], 0);
Continue;
end;
AssignFile(F, FileListBox1.Items.Strings[i]);
Reset(F, 1);
ListBox1.Items.Add(IntToStr(FileSize(F)));
CloseFile(F);
end;
finally
{ do something here }
end;
end;

-----------------------------------------------------------------------------
Halt 结束程式返回作业系统.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Halt [ ( Exitcode: Integer) ];
范例 begin
if 1 = 1 then
begin
if 2 = 2 then
begin
if 3 = 3 then
begin

Halt(1); { Halt right here! }
end;
end;
end;
Canvas.TextOut(10, 10, 'This will not be executed');
end;
-----------------------------------------------------------------------------
RunError 停止程式执行且执行run-time error.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure RunError [ ( Errorcode: Byte ) ];
范例 begin
{$IFDEF Debug}
if P = nil then
RunError(204);
{$ENDIF}
end;

=====================================
I/O routines I/O常式
=====================================
AssignFile 指定档案给一个档案变数.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure AssignFile(var F; FileName: string);
说明 **一个档案不可重复执行AssignFile两次以上.
Example
var
F: TextFile;
S: string;
begin
if OpenDialog1.Execute then { Display Open dialog box }
begin
AssignFile(F, OpenDialog1.FileName); { File selected in dialog box }
Reset(F);
Readln(F, S); { Read the first line out of the file }
Edit1.Text := S; { Put string in a TEdit control }
CloseFile(F);
end;
end;
## AssignFile, OpenDialog, Readln, CloseFile Example

** Write(F,I1:10:2,I2:8:2);
具有格式化的功能,如同Str.

范例 procedure TForm1.Button1Click(Sender: TObject);
var
F: file of Byte;
I1,I2,I3:Byte;
begin
I1:=16;
I2:=32;
I3:=48;
AssignFile(F,'c:\ka\aaa.txt');
Rewrite(F);
Write(F,I1);
Write(F,I2);
Write(F,I3);
Write(F,I1,I2,I3);

I1:=0;
Reset(F);
Read(F, I1);

Label1.Caption:=IntToStr(I1);
CloseFile(F);
end;

结果 file of Byte 及 file of record
只能以Write及Read,来写入及读取,
不可以Writeln及Readln.

范例 procedure TForm1.Button1Click(Sender: TObject);
type
ppRec = record
pp_No:String[5];
pp_Name:String[10];
pp_Age:Integer;
pp_Sum:Double;
end;
var
Rec : ppRec;
Rec2: ppRec;
F: file of ppRec;
begin
With Rec do
Begin
pp_No:='0001';
pp_Name:='abc';
pp_Age:=12;
pp_Sum:=600;
End;

AssignFile(F,'c:\ka\aaa.txt');
Rewrite(F);
Write(F,Rec);

Rec.pp_No:='0002';
Rec.pp_Sum:=58.2;
Write(F,Rec);

Rec.pp_No:='0003';
Rec.pp_Sum:=258.242;
Write(F,Rec);

seek(F,1);
Read(F,Rec2);

seek(F,1);
Truncate(F); {删除,只剩第0笔}

Canvas.TextOut(5,10,Rec2.pp_No);
Canvas.TextOut(5,30,Rec2.pp_Name);
Canvas.TextOut(5,50,Format('%d',[Rec2.pp_Age]));
Canvas.TextOut(5,70,Format('%f',[Rec2.pp_Sum]));

CloseFile(F);
end;

结果 pp_No存入6 Bytes
pp_Name存入11 Bytes
pp_Age存入4 Bytes(Integer 4 Bytes)
pp_Sum存入8 Bytes(Double 8 Bytes)

整个Record以16的倍数存档.
EXAMPLE
var F: TextFile;
begin
AssignFile(F, 'NEWFILE.$ );
Rewrite(F);
Writeln(F, 'Just created file with this text in it...');
CloseFile(F);
end;

-----------------------------------------------------------------------------
Eof 测试档案是否结束.
-----------------------------------------------------------------------------
Unit System
函数原型 function Eof(var F): Boolean;
函数原型 function Eof [ (var F: Text) ]: Boolean;
范例 var
F1, F2: TextFile;
Ch: Char;
begin
if OpenDialog1.Execute then
begin
AssignFile(F1, OpenDialog1.Filename);
Reset(F1);

if SaveDialog1.Execute then
begin
AssignFile(F2, OpenDialog1.Filename);
Rewrite(F2);
while not Eof(F1) do
begin
Read(F1, Ch);
Write(F2, Ch);
end;
CloseFile(F2);
end;
CloseFile(F1);
end;
end;
Example
var

F1, F2: TextFile;
Ch: Char;
begin
if OpenDialog1.Execute then begin
AssignFile(F1, OpenDialog1.Filename);
Reset(F1);
if SaveDialog1.Execute then begin
AssignFile(F2, SaveDialog1.Filename);
Rewrite(F2);
while not Eof(F1) do
begin
Read(F1, Ch);
Write(F2, Ch);
end;
CloseFile(F2);
end;
CloseFile(F1);
end;
end;
-----------------------------------------------------------------------------
OpenPictureDialog OpenDialog 开启档案.
-----------------------------------------------------------------------------
//SavePictureDialog1.DefaultExt := GraphicExtension(TBitmap);
//SavePictureDialog1.Filter := GraphicFilter(TBitmap);

procedure TForm1.Button1Click(Sender: TObject);
var

Done: Boolean;
begin
OpenPictureDialog1.DefaultExt := GraphicExtension(TIcon);
OpenPictureDialog1.FileName := GraphicFileMask(TIcon);
OpenPictureDialog1.Filter := GraphicFilter(TIcon);
OpenPictureDialog1.Options := [ofFileMustExist, ofHideReadOnly, ofNoChangeDir ];
while not Done do
begin
if OpenPictureDialog1.Execute then
begin
if not (ofExtensionDifferent in OpenPictureDialog1.Options) then

begin
Application.Icon.LoadFromFile(OpenPictureDialog1.FileName);
Done := True;
end
else
OpenPictureDialog1.Options := OpenPictureDialog1.Options - ofExtensionDifferent;
end
else { User cancelled }
Done := True;
end;
end;

## Eof, Read, Write Example
-----------------------------------------------------------------------------
Erase 删除档案.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Erase(var F);
说明 要先关档後才可以执行.
范例 procedure TForm1.Button1Click(Sender: TObject);
var
F: Textfile;
begin
OpenDialog1.Title := 'Delete File';
if OpenDialog1.Execute then
begin
AssignFile(F, OpenDialog1.FileName);
try
Reset(F);
if MessageDlg('Erase ' + OpenDialog1.FileName +
'?',mtConfirmation, [mbYes, mbNo], 0) = mrYes then
begin

CloseFile(F);
Erase(F);
end;
except
on EInOutError do
MessageDlg('File I/O error.', mtError, [mbOk], 0);
end;
end;
end;
Example
procedure TForm1.Button1Click(Sender: TObject);

var
F: Textfile;
begin
OpenDialog1.Title := 'Delete File';
if OpenDialog1.Execute then begin
AssignFile(F, OpenDialog1.FileName);
try
Reset(F);
if MessageDlg('Erase ' + OpenDialog1.FileName + '?',
mtConfirmation, [mbYes, mbNo], 0) = mrYes then
begin
CloseFile(F);
Erase(F);
end;
except
on EInOutError do

MessageDlg('File I/O error.', mtError, [mbOk], 0);
end;
end;
end;
##Erase, OpenDialog.Title, OpenDialog.FileName Example
-----------------------------------------------------------------------------
Rename 更改档名.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Rename(var F; Newname);
范例 uses Dialogs;
var
f : file;
begin
OpenDialog1.Title := 'Choose a file... ';

if OpenDialog1.Execute then
begin
SaveDialog1.Title := 'Rename to...';
if SaveDialog1.Execute then
begin
AssignFile(f, OpenDialog1.FileName);
Canvas.TextOut(5, 10, 'Renaming ' +
OpenDialog1.FileName +' to ' +
SaveDialog1.FileName);
Rename(f, SaveDialog1.FileName);
end;
end;
end;
Example
uses Dialogs;
var

f : file;
begin
OpenDialog1.Title := 'Choose a file... ';
if OpenDialog1.Execute then begin
SaveDialog1.Title := 'Rename to...';
if SaveDialog1.Execute then begin
AssignFile(f, OpenDialog1.FileName);
Canvas.TextOut(5, 10, 'Renaming ' + OpenDialog1.FileName + ' to ' +
SaveDialog1.FileName);
Rename(f, SaveDialog1.FileName);
end;
end;
end;
-----------------------------------------------------------------------------
GetDir 传回指定磁碟机的目录.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure GetDir(D: Byte; var S: string);
说明 D
0=目前磁碟机,1=A磁碟机,2=B磁碟机....
**此函式不检查磁碟机错误.
范例 var
s : string;
begin
GetDir(0,s); { 0 = Current drive }
MessageDlg('Current drive and directory: ' + s,
mtInformation, [mbOk] , 0);
end;

======================================
Miscellaneous routines 其他常式
======================================
Exclude 删除一组元素中的一个元素.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Exclude(var S: set of T;I:T);
说明 删除S中的I元素.
-----------------------------------------------------------------------------
FillChar 填入元素.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure FillChar(var X; Count: Integer; value);
说明 以value填入X中Count个.

范例 Example
var
S: array[0..79] of char;
begin
{ Set to all spaces }
FillChar(S, SizeOf(S), Ord(' '));
MessageDlg(S, mtInformation, [mbOk], 0);
end;
-----------------------------------------------------------------------------
Hi 传回高位元数字.
-----------------------------------------------------------------------------
Unit System
函数原型 function Hi(X): Byte;
范例 var B: Byte;
begin
B := Hi($1234); { $12 }
end;
-----------------------------------------------------------------------------
Include 加入一个元素到一组元素.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Include(var S: set of T; I:T);
说明 加入I元素到S中.
-----------------------------------------------------------------------------
Lo 传回高位元数字.

-----------------------------------------------------------------------------
Unit System
函数原型 function Lo(X): Byte;
范例 var B: Byte;
begin
B := Lo($1234); { $34 }
end;
-----------------------------------------------------------------------------
Move 从来源变数拷贝n个Bytes到目的变数.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Move(var Source, Dest; Count: Integer);
范例 var
A: array[1..4] of Char;
B: Integer;
begin
Move(A, B, SizeOf(B));
{ SizeOf = safety! }
end;
-----------------------------------------------------------------------------
ParamCount 直接由执行档後加上传入变数的个数.(arj.exe a dr.arj d:*.*)
-----------------------------------------------------------------------------
Unit System
函数原型 function ParamCount: Integer;
说明 如上例则传回3
Example
var

I: Integer;
ListItem: string;
begin
for I := 0 to IBQuery1.ParamCount - 1 do
begin
ListItem := ListBox1.Items[I];
case IBQuery1.Params[I].DataType of
ftString:
IBQuery1.Params[I].AsString := ListItem;
ftSmallInt:
IBQuery1.Params[I].AsSmallInt := StrToIntDef(ListItem, 0);
ftInteger:
IBQuery1.Params[I].AsInteger := StrToIntDef(ListItem, 0);
ftWord:

IBQuery1.Params[I].AsWord := StrToIntDef(ListItem, 0);

ftBoolean:
begin
if ListItem = 'True' then
IBQuery1.Params[I].AsBoolean := True
else
IBQuery1.Params[I].AsBoolean := False;
end;
ftFloat:
IBQuery1.Params[I].AsFloat := StrToFloat(ListItem);
ftCurrency:
IBQuery1.Params[I].AsCurrency := StrToFloat(ListItem);
ftBCD:

IBQuery1.Params[I].AsBCD := StrToCurr(ListItem);
ftDate:
IBQuery1.Params[I].AsDate := StrToDate(ListItem);
ftTime:
IBQuery1.Params[I].AsTime := StrToTime(ListItem);
ftDateTime:
IBQuery1.Params[I].AsDateTime := StrToDateTime(ListItem);
end;
end;
end;
##ParamCount, DataType, StrToIntDef, AsXXX Example
-----------------------------------------------------------------------------
ParamStr
-----------------------------------------------------------------------------
Unit System
函数原型 function ParamStr(Index: Integer): string;
说明 ParamStr(0);传回执行档的名称及完整目录.
(C:\ZIP\ARJ.EXE)
范例
var
I: Word;
Y: Integer;
begin
Y := 10;
for I := 1 to ParamCount do
begin
Canvas.TextOut(5, Y, ParamStr(I));
Y := Y + Canvas.TextHeight(ParamStr(I)) + 5;
end;
end;
Example
procedure TForm1.FormCreate(Sender: TObject);

var
i: Integer;
for i := 0 to ParamCount -1 do
begin
if LowerCase(ParamStr(i)) = 'beep' then
Windows.Beep(10000,1000)
else
if (LowerCase(ParamStr(i)) = 'exit' then
Application.Terminate;
end;
end;
##ParamCount, ParamStr Example
-----------------------------------------------------------------------------
Random 乱数
-----------------------------------------------------------------------------
Unit System
函数原型 function Random [ ( Range: Integer) ];
说明 0<=X<Range
范例 var
I: Integer;
begin
Randomize;
for I := 1 to 50 do
begin
{ Write to window at random locations }
Canvas.TextOut(Random(Width), Random(Height),
'Boo!');
end;
end;

-----------------------------------------------------------------------------
Odd 检查是否为奇数.
-----------------------------------------------------------------------------
Unit System
函数原型 function Odd(X: Longint): Boolean;
Example
begin

if Odd(5) then
Canvas.TextOut(10, 10, '5 is odd.')
else
Canvas.TextOut(10, 10, 'Something is odd!');
end;
=======================================
Pointer and address routines 位址常式
=======================================
Addr 传回一个物件的位址.
-----------------------------------------------------------------------------
Unit System
函数原型 function Addr(X): Pointer;
Example
var
I : Integer;
NodeNumbers: array [0 .. 100] of Integer;
begin
with TreeView1 do
begin
for I := 0 to Items.Count - 1 do
begin
NodeNumbers[I] := CalculateValue(Items[I]);
Items[I].Data := Addr(NodeNumber[I]);
end;
end;
end;
-----------------------------------------------------------------------------
Assigned 测试指标变数是否为nil.

-----------------------------------------------------------------------------
Unit System
函数原型 function Assigned(var P): Boolean;
说明 当@P=nil ==> 传回FALSE
范例 var P: Pointer;
begin
P := nil;
if Assigned (P) then
Writeln ('You won't see this');
GetMem(P, 1024); {P valid}
FreeMem(P, 1024); {P no longer valid and still not nil}
if Assigned (P) then
Writeln ('You'll see this');
end
===================================
String-formatting routines 字串格式化
==================================
FmtStr 格式化.
-----------------------------------------------------------------------------
FmtStr(var StrResult: string;const Format: string;const Args: array of string );

-----------------------------------------------------------------------------
Format
Format(const Format: string;const Args: array of string ): string;
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 procedure FmtStr(var Result: string; const Format: string;
const Args: array of const);
function Format(const Format: string; const Args: array of
const): string;
说明 %d : 整数
%e : 科学式
%f : 定点实数
%g : 实数
%n : 实数(-d,ddd,ddd.dd ...)
%m: 金钱格式
%p : point
%s : 字串
%x : Hex
范例 var
i: Integer;
j: Double;
s: String;
t: String;

begin
t:=Format('%d %8.2f %s',[i,j,s]);
ListBox1.Item.Add(t);
end;

BubbleSeries1.PercentFormat := '##0.0# %';
Example
procedure TForm1.Table1AfterDelete(DataSet: TDataSet);
begin
StatusBar1.SimpleText := Format('There are now %d records in the table', [DataSet.RecordCount]);
end;

S:= Format( '1-? ??????? ??????? - %d, 2-? - %d, 3-? - %d', [10,20,30] );




Format( '%*.*f', [ 9, 2, 12345.6789 ] );
Format( '%9.2f', [ 12345.6789 ] );
Format( '%3d, %d, %0:d, %2:-4d, %d', [ 1, 2, 3, 4 ] );
' 1,2,1,3 ,4'


## AfterDelete, Format Example


=======================================
String-handling routines (Pascal-style) 字串函式
=======================================
AnsiCompareStr 比较两个字串的大小.依安装的 language driver.
-----------------------------------------------------------------------------
AnsiCompareText ( AnsiCompareText 此项不分大小写 ).
-----------------------------------------------------------------------------
Unit SysUtils
var

S1,S2: string;
I: Integer;

begin

S1:= 'A????';
S2:= '?????';

I:= CompareStr(S1, S2); { I = 0, ?.?. S1 = S2 }
if I=0 then
MessageDlg(S1, '=', S2, mtWarning, [mbOK], 0);
end;

函数原型 function AnsiCompareStr(const S1, S2: string):Integer;
函数原型 function AnsiCompareText(const S1, S2: string):Integer;

-----------------------------------------------------------------------------
Delete 删除字串中的数个字元.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Delete(var S: string; Index, Count:Integer);
说明 S : 字串.
Indexd : 从第几位开始删.
Count : 总共要删几位.
范例 var
s: string;
begin
s := 'Honest Abe Lincoln';
Delete(s,8,4);
Canvas.TextOut(10, 10, s); { 'Honest Lincoln' }
end;
var
S: string;
begin
S:= '???????, ??????, ??????????!';
Delete(S, 8, 1); // S := '??????? ??????, ??????????!'
MessageDlg(S, mtWarning, [mbOK],0);
end;
-----------------------------------------------------------------------------
NewStr 在 heap 中配置一个新的字串空间给PString 指标.
-----------------------------------------------------------------------------
DisposeStr 在 heap 中释放一个字串空间 PString指标.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function NewStr(const S: string): PString;
函数原型 procedure DisposeStr(P: PString);
说明 S : 字串.
Pstring : 新的字串指标.
范例 var
P: PString;
S: string;
begin
S := 'Ask me about Blaise';
P := NewStr(S);
DisposeStr(P):

end;
-----------------------------------------------------------------------------
Insert 将一个子字串插入另一个字串中.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Insert(Source: string; var S: string; Index: Integer);
说明 Source : 子字串.
S : 被插入的母字串.
Indexd : 从第几位开始插入.
范例 var
S: string;
begin
S := 'Honest Lincoln';
Insert('Abe ', S, 8); { 'Honest Abe Lincoln' }
end;
var
S: string;
begin
S:= '??????? ?????? ??????????.';
Insert( '!', S, 8); { S := '???????! ?????? ??????????.'}
MessageDlg( S, mtWarning, [mbOK],0);
end;
-----------------------------------------------------------------------------
IntToHex 将 Int 转为 Hex.
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);

var
i: Integer;
begin
Label1.Caption := ';
for i := 1 to Length(Edit1.Text) do
begin
try
Label1.Caption := Label1.Caption + IntToHex(Edit1.Text[i],4) + ' ';
except
Beep;
end;
end;
end;

Exam:

Edit2.text:=(strtoint(Edit1.text),6);

-----------------------------------------------------------------------------
IntToStr 将 Int 转为 Str.
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);
begin
try
Label1.Caption := IntToStr(StrToInt(Edit1.Text) * StrToInt(Edit2.Text));
except
ShowMessage('You must specify integer values. Please try again.');
end;
end;
-----------------------------------------------------------------------------
StrToInt 将 Str 转为 Int.
-----------------------------------------------------------------------------
procedure TForm1.Button1Click(Sender: TObject);
var
I: Integer;
J: Integer;
begin
I := StrToInt(Edit1.Text);
J := StrToInt(Edit2.Text);
ShowMessage(IntToStr(I + J));
end;
-----------------------------------------------------------------------------
StrToIntDef 将 Str 转为 Int.当转换有误时,则传回 Default 的值.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function IntToHex(Value: Integer; Digits: Integer): string;
函数原型 function IntToStr(Value: Integer): string;
函数原型 function StrToInt(const S: string): Integer;
函数原型 function StrToIntDef(const S: string; Default: Integer): Integer;
说明 Value : 欲转换的整数.
Digits : 欲转换为几位数的 Hex.
范例 procedure TForm1.Button1Click(Sender: TObject);
begin
Edit2.Text := IntToHex(StrToInt(Edit1.Text), 6);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
Value: Integer;
begin
Value := 1234;
Edit1.Text := IntToStr(Value);

end;

procedure TForm1.Button1Click(Sender: TObject);
var
S: string;
I: Integer;
begin
S := '22467';
I := StrToInt(S);
Inc(I);
Edit1.Text := IntToStr(I);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
NumberString: string;
Number: Integer;
begin
NumberString := Edit1.Text;
Number := StrToIntDef(NumberString, 1000);
Edit2.Text := IntToStr(Number);
end;
Example
var

I: Integer;
ListItem: string;
begin
for I := 0 to Query1.ParamCount - 1 do
begin
ListItem := ListBox1.Items[I];
case Query1.Params[I].DataType of
ftString:
Query1.Params[I].AsString := ListItem;
ftSmallInt:
Query1.Params[I].AsSmallInt := StrToIntDef(ListItem, 0);
ftInteger:
Query1.Params[I].AsInteger := StrToIntDef(ListItem, 0);
ftWord:
Query1.Params[I].AsWord := StrToIntDef(ListItem, 0);

ftBoolean:
begin
if ListItem = 'True' then

Query1.Params[I].AsBoolean := True
else
Query1.Params[I].AsBoolean := False;
end;
ftFloat:
Query1.Params[I].AsFloat := StrToFloat(ListItem);
ftCurrency:
Query1.Params[I].AsCurrency := StrToFloat(ListItem);
ftBCD:
Query1.Params[I].AsBCD := StrToCurr(ListItem);
ftDate:

Query1.Params[I].AsDate := StrToDate(ListItem);
ftTime:
Query1.Params[I].AsTime := StrToTime(ListItem);
ftDateTime:
Query1.Params[I].AsDateTime := StrToDateTime(ListItem);
end;
end;
end;
--------------------------
procedure TForm1.Button1Click(Sender: TObject);
var
Number: Integer;
begin
Number := StrToIntDef(Edit1.Text, 1000);
Edit2.Text := IntToStr(Number);
end;
-------------------
## ParamCount, DataType, StrToIntDef, AsXXX Example

-----------------------------------------------------------------------------
Pos 寻找子字串在母字串中的位置.
-----------------------------------------------------------------------------
Unit System
函数原型 function Pos(Substr: string; S: string): Integer;
说明 Substr : 子字串.
S : 母字串.
范例
procedure TForm1.Button1Click(Sender: TObject);
var S: string;
begin
S := ' 1234.5 ';
{ Convert spaces to zeroes }
while Pos(' ', S) > 0 do
S[Pos(' ', S)] := '0';
Label1.Caption := S;
Label1.Font.Size := 16;
end;

var
S: string;
I: Integer;
begin
S:= '? ???? ???????? ??????';
I:= Pos( '???', S); // I:= 3
end;
//DEMO 001234.50 //空白字串补零
-----------------------------------------------------------------------------
LowerCase 将字串全部转为小写字母.
-----------------------------------------------------------------------------
Unit System
函数原型 function LowerCase(const S: string): string;
范例 procedure TForm1.Button1Click(Sender: TObject);
begin
Edit2.Text := LowerCase(Edit1.Text);
end;
Example
procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption := LowerCase(Edit1.Text);
end;
var
S: string;
begin
S:= LowerCase( '????????.TXT') ; // S := '????????.txt'
end;
-----------------------------------------------------------------------------
UpperCase 将字串全部转为大写字母.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function UpperCase(const S: string): string;
范例 procedure TForm1.Button1Click(Sender: TObject);
var
I: Integer;
begin
for I := 0 to ListBox1.Items.Count -1 do
ListBox1.Items[I] := UpperCase(ListBox1.Items[I]);
end;
Example
procedure TForm1.Button1Click(Sender: TObject);
var
I: Integer;
begin
for I := 0 to ListBox1.Items.Count -1 do
ListBox1.Items[I] := UpperCase(ListBox1.Items[I]);
end;
-----------------------------------------------------------------------------
Trim 将字串前後的空白及控制字元清掉.
Trim ( const S: string ): string;
SysUtils
var
S: string;
L: Integer;
begin
S:= #13' ???! '#13;
L:= length( S); // L := 10
S:= Trim( S); // S := '???!'
L:= L-length( S); // L := 5
MessageDlg( '??????? ???????? - '+ IntToStr(L), mtInformation, [mbOk], 0);
end;

-----------------------------------------------------------------------------
TrimLeft 将字串左边的空白及控制字元清掉.
SysUtils
var
S: string;
L: Integer;
begin
S:= #13' ???! '#13;
L:= length( S); // L := 10
S:= TrimLeft( S); // S := '???! '#13
L:= L-length( S); // L := 3
MessageDlg( '??????? ???????? - '+IntToStr(L), mtInformation, [mbOk], 0);
end;

-----------------------------------------------------------------------------
StrCat 字串相加.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrCat(Dest, Source: PChar): PChar;
范例 uses SysUtils;
const
Obj: PChar = 'Object';
Pascal: PChar = 'Pascal';
var
S: array[0..15] of Char;
begin
StrCopy(S, Obj);
StrCat(S, ' ');
StrCat(S, Pascal);
Canvas.TextOut(10, 10, StrPas(S));
end;
Example
procedure TForm1.Button1Click(Sender: TObject);
var
Buffer: PChar;
begin
GetMem(Buffer,Length(Label1.Caption) + Length(Edit1.Text) + 1);
StrCopy(Buffer, PChar(Label1.Caption));
StrCat(Buffer, PChar(Edit1.Text));
Label1.Caption := Buffer;
Edit1.Clear;
FreeMem(Buffer);
end;

const
P0: PChar = '??????-';
P1: PChar = '??????????';
P2: PChar = '????????';
var
S1, S2: array[0..20] of Char;
begin
StrCopy(S1, P0);
StrCopy(S2, P0);
StrCat(S1, P1); { S1 := '??????-??????????' }
StrCat(S2, P2); { S2 := '??????-????????' }
MessageDlg( S1+ #13+ S2, mtInformation, [mbOk], 0);
end;

##StrCopy, StrCat Example
-----------------------------------------------------------------------------
StrComp 比较两字串大小.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrComp(Str1, Str2 : PChar): Integer;
范例 uses SysUtils;
const
S1: PChar = 'Wacky';
S2: PChar = 'Code';
var
C: Integer;
Result: string;
begin
C := StrComp(S1, S2);
if C < 0 then Result := ' is less than ' else
if C > 0 then Result := ' is greater than ' else
Result := ' is equal to ';
Canvas.TextOut(10, 10, StrPas(S1) + Result +
StrPas(S2));
end;
Example
uses SysUtils;
procedure TForm1.Button1Click(Sender: TObject);

var
Msg: string;
CompResult: Integer;
begin
Msg := Edit1.Text;
CompResult := StrComp(PChar(Edit1.Text), PChar(Edit2.Text));
if CompResult < 0 then
Msg := Msg + ' is less than '
else if CompResult > 0 then
Msg := Msg + ' is greater than '
else
Msg := Msg + ' is equal to '
Msg := Msg + Edit2.Text;
ShowMessage(Msg);
end;

var
S1,S2: PChar;
I: Integer;
Res: string;
begin
S1:= 'Company';
S2:= 'COMPANY';
I:= StrComp(S1, S2);
if I>0 then Res:= '>' else
if I<0 then Res:= '<' else Res:= '=';
MessageDlg(S1+ Res+ S2, mtInformation, [mbOk], 0);
end;

-----------------------------------------------------------------------------
StrIComp 比较两字串大小.(不分大小写)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrIComp(Str1, Str2:PChar): Integer;
范例 uses SysUtils;
const
S1: PChar = 'Wacky';
S2: PChar = 'Code';
var
C: Integer;
Result: string;
begin
C := StrIComp(S1, S2);
if C < 0 then Result := ' is less than ' else
if C > 0 then Result := ' is greater than ' else
Result := ' is equal to ';
Canvas.TextOut(10, 10, StrPas(S1) + Result +
StrPas(S2));
end;
xample
uses SysUtils;
procedure TForm1.Button1Click(Sender: TObject);

var
Msg: string;
CompResult: Integer;
begin
Msg := Edit1.Text;
CompResult := StrIComp(PChar(Edit1.Text), PChar(Edit2.Text));
if CompResult < 0 then
Msg := Msg + ' is less than '
else if CompResult > 0 then
Msg := Msg + ' is greater than '
else
Msg := Msg + ' is equal to '
Msg := Msg + Edit2.Text;
ShowMessage(Msg);
end;

var
S1,S2: PChar;
I: Integer;
Res: string;
begin
S1:= 'ABC';
S2:= 'abc';
I:= StrIComp(S1, S2); { I := 0, ?.?. S1 = S2 }
if I>0 then Res:= '>' else
if I<0 then Res:= '<' else Res:= '=';
MessageDlg( S1 + Res + S2, mtInformation, [mbOk], 0);
end;
-----------------------------------------------------------------------------
StrLCat 字串相加.(指定长)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrLCat(Dest, Source: PChar; MaxLen: Cardinal):
PChar;
范例 uses SysUtils;
var
S: array[0..13] of Char;
begin
StrLCopy(S, 'Object', SizeOf(S) - 1);
StrLCat(S, ' ', SizeOf(S) - 1);
StrLCat(S, 'Pascal', SizeOf(S) - 1);
Canvas.TextOut(10, 10, StrPas(S));
end;
Example
procedure TForm1.Button1Click(Sender: TObject);
var
FirstHalf: PChar;
SecondHalf: PChar;
HalfLen: Integer;
begin
HalfLen := StrLen(PChar(Edit1.Text)) div 2;
GetMem(FirstHalf,HalfLen+2);
GetMem(SecondHalf,HalfLen+2);
FirstHalf^ := Chr(0);
SecondHalf^ := Chr(0);
StrLCat(FirstHalf, PChar(Edit1.Text), HalfLen);
StrCat(SecondHalf, PChar(Edit1.Text) + HalfLen);
Application.MessageBox(FirstHalf, 'First Half', MB_OK);
Application.MessageBox(SecondHalf, 'Second Half', MB_OK);
FreeMem(FirstHalf);
FreeMem(SecondHalf);
end;

const
S1: PChar = '???';
S2: PChar = '?????????';
var
S: array[0..13] of Char;
begin
StrLCopy(S, S1, StrLen(S1));
StrLCat(S, S2, 6); { S :='??????' }
MessageDlg(S, mtInformation, [mbOk], 0);
end;
## StrLen, StrLCat Example
-----------------------------------------------------------------------------
StrLComp 比较两字串大小.(指定长)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrLComp(Str1, Str2: PChar; MaxLen: Cardinal):
Integer;
范例 uses SysUtils;
const
S1: PChar = 'Enterprise'
S2: PChar = 'Enter'
var
Result: string;
begin
if StrLComp(S1, S2, 5) = 0 then
Result := 'equal'
else
Result := 'different';
Canvas.TextOut(10, 10, 'The first five characters are ' +
Result);
end;
example
uses SysUtils;
const
S1: PChar = 'Enterprise'
S2: PChar = 'Enter'
var
ComStr: string;
begin
if StrLComp(S1, S2, 5) = 0 then
ComStr := 'equal'
else
ComStr := 'different';
Canvas.TextOut(10, 10, 'The first five characters are ' + ComStr);
end;
const
S1: PChar = '?????????';
S2: PChar = '????????';
var
I: Integer;
S: string;
begin
I:= 5;
if StrLComp( S1, S2, I) = 0 then S:= '?????' else S:= '????????';
MessageDlg( '?????? '+ IntToStr(I)+ ' ???????? ????? '+ S, mtInformation,[mbOk], 0);
end;

-----------------------------------------------------------------------------
StrLIComp 比较两字串大小.(指定长,不分大小写)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrLIComp(Str1, Str2: PChar; MaxLen:
Cardinals): Integer;
范例 uses SysUtils;
const
S1: PChar = 'Enterprise'
S2: PChar = 'Enter'
var
Result: string;
begin
if StrLIComp(S1, S2, 5) = 0 then
Result := 'equal'
else
Result := 'different';
Canvas.TextOut(10, 10, 'The first five characters are ' +
Result);
end;
Examply
uses SysUtils;
const

S1: PChar = 'Enterprise'
S2: PChar = 'Enter'

var
ComStr: string;
begin
if StrLIComp(S1, S2, 5) = 0 then
ComStr := 'equal'
else
ComStr := 'different';
Canvas.TextOut(10, 10, 'The first five characters are ' + ComStr);
end;


const
S1: PChar = '?????????';
S2: PChar = '????????';
var
S: string;
begin
if StrLIComp( S1, S2, 5) = 0 then S:= '?????' else S:= '????????';
MessageDlg( S1 + #13 + S2 + #13 + '?????? ' + IntToStr( I) + ' ???????? ????? ' + S, mtInformation, [mbOk], 0);
end;
-----------------------------------------------------------------------------
StrLower 将字串全部转为小写字母.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrLower(Str: PChar): PChar;
范例 uses SysUtils;
const
S: PChar = 'A fUnNy StRiNg'
begin
Canvas.TextOut(5, 10, StrPas(StrLower(S)) + ' ' +
StrPas(StrUpper(S)));
end;
-----------------------------------------------------------------------------
StrMove 从来源字串拷贝n个Bytes到目爬r串.(不含终止位元)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrMove(Dest, Source: PChar; Count:
Cardinal): PChar;
范例 uses SysUtils;
function AHeapaString(S: PChar): PChar;
{ Allocate string on heap }
var
L: Cardinal;
P: PChar;
begin
StrNew := nil;
if (S <> nil) and (S[0] <> #0) then
begin
L := StrLen(S) + 1;
GetMem(P, L);
StrNew := StrMove(P, S, L);
end;
end;
procedure DisposeDaString(S: PChar);
{ Dispose string on heap }
begin
if S <> nil then FreeMem(S, StrLen(S) + 1);
end;
var
S: PChar;
begin
AHeapaString(S);
DisposeDaString(S);
end;
var
S1, S2: PChar;
begin
S1:= 'ABcdEFgh';
StrMove( S2, S1, StrLen( S1) + 1 );
StrLower( S1); { S1:= 'abcdefgh' }
StrUpper( S2); { S2:= 'ABCDEFGH' }
MessageDlg( S1 + #13#10 + S2, mtInformation, [mbOk], 0);
end;

-----------------------------------------------------------------------------
StrPCopy 拷贝 Pascal-style 字串到null-terminated 字串.
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrPCopy(Dest: PChar; Source: string): PChar;
范例 uses SysUtils;
var
A: array[0..79] of Char;
S: String;
begin
S := 'Honk if you know Blaise.';
StrPCopy(A, S);
Canvas.TextOut(10, 10, StrPas(A));
end;

var
Source: string;
Dest: array[0..20] of Char;
begin
Source:= '???????? ??????';
StrPCopy( Dest, Source);
MessageDlg( Dest, mtInformation, [mbOk], 0);
end;
-----------------------------------------------------------------------------
StrPLCopy 拷贝 Pascal-style 字串到null-terminated 字串.(指定长)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrPLCopy(Dest: PChar; const Source: string;
MaxLen: Cardinal): PChar;
-----------------------------------------------------------------------------
StrPos 子字串在母字串中的位置.(第一个位置)
-----------------------------------------------------------------------------
Unit SysUtils
函数原型 function StrPos(Str1, Str2: PChar): PChar;
说明 Str1 母字串
Str2 子字串
Example
uses SysUtils;

procedure TForm1.Button1Click(Sender TObject);
var
Location: PChar;
begin
if StrPos(PChar(Edit1.Text), PChar(Edit2.Text)) <> nil
then
ShowMessage('Substring found')
else
ShowMessage('Substring not found');
end;
------------------
const
SubStr: PChar = 'www';
var
S, R: PChar;
begin
S:= 'http://www.atrussk.ru/delphi/';
R:= StrPos(S, SubStr);
if R<>nil then MessageDlg( R, mtInformation, [mbOk], 0) else
MessageDlg( '?? ????????? ?????? URL!', mtError, [mbOk], 0);
end;

=========================================
Text-file routines Text-file常式
=========================================
Append 开起一个可供Append的档案.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Append(var f: Text);
范例 var F: TextFile;
begin
if OpenDialog1.Execute then
{ Bring up open file dialog }
begin
AssignFile(F, OpenDialog1.FileName);
{ Open file selected in dialog }
Append(F); { Add more text onto end }
Writeln(F, 'appended text');
CloseFile(F); { Close file, save changes }
end;
end;
Example
var

f: TextFile;
begin
if OpenDialog1.Execute then
begin { open a text file }
AssignFile(f, OpenDialog1.FileName);
Append(f);
Writeln(f, 'I am appending some stuff to the end of the file.');
{ insert code here that would require a Flush before closing the file }
Flush(f); { ensures that the text was actually written to file }
CloseFile(f);
end;
end;
## Append, Flush Example
-----------------------------------------------------------------------------
Eoln 测试档案是否结束.(For text file.)
-----------------------------------------------------------------------------
Unit System
函数原型 function Eoln [(var F: Text) ]: Boolean;
Flush 将Buffer中的资料存入磁碟.
(For text file)
Unit System
函数原型 procedure Flush(var F: Text);
范例 var
f: TextFile;
begin
if OpenDialog1.Execute then
begin { open a text file }
AssignFile(f, OpenDialog1.FileName);
Append(f);
Writeln(f, 'I am appending some stuff to the end of the
file.');
Flush(f);
{ ensures that the text was actually written to file }
{ insert code here that would require a Flush before
closing the file }
CloseFile(f);
end;
end;
Example
begin
{ Tells program to wait for keyboard input }
WriteLn(Eoln);
end;
-----------------------------------------------------------------------------
Read 读档.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Read(F , V1 [, V2,...,Vn ] );
procedure Read( [ var F: Text; ] V1 [, V2,...,Vn ] );
范例 uses Dialogs;
var
F1, F2: TextFile;
Ch: Char;
begin
if OpenDialog1.Execute then
begin
AssignFile(F1, OpenDialog1.Filename);
Reset(F1);
if SaveDialog1.Execute then
begin
AssignFile(F2, OpenDialog1.Filename);
Rewrite(F2);
While not Eof(F1) do
begin
Read(F1, Ch);
Write(F2, Ch);
end;
CloseFile(F2);
end;
CloseFile(F1);
end;
end.

-----------------------------------------------------------------------------
SetTextBuf 指定 I/O buffer 给 text file.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure SetTextBuf(var F: Text; var Buf [ ; Size: Integer] );
范例 uses Dialogs;
var
F, FTwo: System.TextFile;
Ch: Char;
Buf: array[1..4095] of Char; { 4K buffer }
begin
if OpenDialog1.Execute then
begin
AssignFile(F, ParamStr(1));
{ Bigger buffer for faster reads }
SetTextBuf(F, Buf);
Reset(F);
{ Dump text file into another file }
AssignFile(FTwo, 'WOOF.DOG');
Rewrite(FTwo);
while not Eof(f) do
begin
Read(F, Ch);
Write(FTwoCh);
end;
System.CloseFile(F);
System.CloseFile(FTwo);
end;
end;
-----------------------------------------------------------------------------
Write 写入档案.
-----------------------------------------------------------------------------
Unit System



函数原型 Write(F, V1,...,Vn);
Write( [var F: Text; ] P1 [ , P2,..., Pn] );
procedure TForm1.Button3Click(Sender: TObject);

var
Stream: TBlobStream;
S: string;
begin
with Table1 do
begin

Edit;

Stream := CreateBlobStream(FieldByName('Notes'), bmReadWrite);
try
Stream.Seek(0, 2); {Seek 0 bytes from the stream's end point}
S := ' This line will be added to the end.';
Stream.Write(PChar(S), Length(S));
finally
Stream.Free;
end;
Post;
end;
end;
-----------------------------------------------------------------------------
Writeln 写入档案.
-----------------------------------------------------------------------------
Unit System
函数原型 procedure Writeln([ var F: Text; ] P1 [, P2, ...,Pn ] );
范例 var
s : string;
begin
Write('Enter a line of text: ');
Readln(s);
Writeln('You typed: ',s);
Writeln('Hit <Enter> to exit');
Readln;
end;

-----------------------------------------------------------------------------
High 传回注脚的最大值.
-----------------------------------------------------------------------------
Unit System
函数原型 function High(X);
范例 [Ordinal type]
procedure TForm1.Button1Click(Sender: TObject);
var
Low_S:String;
High_S:string;
S:String;
begin
High_S:=' High='+IntToStr(High(Word));
Low_S:='Low='+IntToStr(Low(Word));
S:=Low_S+High_S;
Label1.Caption:=S;
end;

S:=Low=0 High=65535

[Array type]
procedure TForm1.Button1Click(Sender: TObject);
var
P : Array[5..21] of Double;
Low_S:String;
High_S:string;
S:String;
begin
High_S:=' High='+IntToStr(High(P));
Low_S:='Low='+IntToStr(Low(P));
S:=Low_S+High_S;
Label1.Caption:=S;
end;

S:=Low=5 High=21

[String type]
procedure TForm1.Button1Click(Sender: TObject);
var
P : String[23];
Low_S:String;
High_S:string;
S:String;
begin
High_S:=' High='+IntToStr(High(P));
Low_S:='Low='+IntToStr(Low(P));
S:=Low_S+High_S;
Label1.Caption:=S;
end;

S:=Low=0 Hight=23

P:ShortString;
S:=Low=0 Hight=255

P:String;
长字串不可,会有错误讯号.

[Open array]
function Sum( var X: array of Double): Double;
var
I: Word;
S: Double;
begin
S := 0;
{ Note that open array index range is always zero-based. }
for I := 0 to High(X) do S := S + X[I];
Sum := S;
end;
Example
function Sum( var X: array of Double): Double;

var
I: Word;
S: Real;
begin
S := 0; { Note that open array index range is always zero-based. }
for I := 0 to High(X) do S := S + X[I];
Sum := S;
end;

procedure TForm1.Button1Click(Sender: TObject);

var
List1: array[0..3] of Double;
List2: array[5..17] of Double;
X: Word;
S, TempStr: string;
begin
for X := Low(List1) to High(List1) do
List1[X] := X * 3.4;
for X := Low(List2) to High(List2) do
List2[X] := X * 0.0123;
Str(Sum(List1):4:2, S);
S := 'Sum of List1: ' + S + #13#10;
S := S + 'Sum of List2: ';
Str(Sum(List2):4:2, TempStr);

S := S + TempStr;
MessageDlg(S, mtInformation, [mbOk], 0);
end;
## Low, High Example