文件读入问题 - 编程论坛

#2

zzt_4282008-08-22 13:42

补充

文件中数据如下:
18 19 18.5 13.5 14
16 19.5 20 18 12 18.5

#3

zerocn2008-08-22 17:25

程序代码：

#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

const int SIZE = 60;
int main()
{
    char fileName[SIZE];
    ifstream inFile;

    cout << "Please enter the file name:";
    cin.getline(fileName,SIZE);
    inFile.open(fileName);
    if(!inFile.is_open())
    {
        cout << "Sorry! This file can't open ."
             << "Program terminating.";
        exit(EXIT_FAILURE);
    }
    double value;
    double sum=0;
    int count=0;

    //inFile>>value;这个要去掉，因为运行了这个后，文件指针已经指向了后面，你试着只分析3个数据就会明白的
    while(inFile.good())
    {   inFile >> value;
        ++count;
        sum += value;

    }
    if(inFile.eof())
        cout << "It's the end of the file.\n";
    else if(inFile.fail())
        cout << "Input terminated by data mismatch.\n";
    else
        cout << "Input terminated by unknown reason.\n";

    if(0 == count)
        cout << "No data processed.\n";
    else
    {
        cout << "Items read:" << count << endl;
        cout << "Sum:" << sum << endl;
        cout << "Average:" << sum/count << endl;
    }
    inFile.close();


    return 0;
}

#4

zzt_4282008-08-22 19:25

总结

上面说的对,但是也可以不把inFile >> value 去掉!
可以把
while(inFile.good())
{
    inFile >> value;  //这一行放到
    ++count;
    sum += value;
    //这里来

}

#5

xqls_xqls2008-08-22 20:51

#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

const int SIZE = 60;
int main()
{
    char fileName[SIZE];
    ifstream inFile;

    cout << "Please enter the file name:";
    cin.getline(fileName,SIZE);
    inFile.open(fileName);
    if(!inFile.is_open())
    {
        cout<< "Sorry! This file can't open ."
            << "Program terminating.";
        exit(EXIT_FAILURE);
    }
    double value;
    double sum=0;
    int count=0;


    while(inFile>>value) //改成这样就可以了
    {
        ++count;
        sum += value;
        //inFile>>value;

    }
    if(inFile.eof())
        cout << "It's the end of the file.\n";
    else if(inFile.fail())
        cout << "Input terminated by data mismatch.\n";
    else
        cout << "Input terminated by unknown reason.\n";

    if(count==0)
        cout << "No data processed.\n";
    else
    {
        cout << "Items read:" << count << endl;
        cout << "Sum:" << sum << endl;
        cout << "Average:" << sum/count << endl;
    }
    inFile.close();
    system("pause");
    return 0;
}