【提问】读取文件的时候读取不完全是怎么回事？

提供的信息有些少

#include <fstream>
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
struct tongxunlu
{
    int num;
    string name;
    string address;
    int tel;
    int youbian;
    string email;
};
void insertdata();//添加数据
void deletdata();//删除数据
void checkdata();//查询数据
void resetdata();//数据排序
tongxunlu data[40];
int main()
{
    cout<<"请输入要进行的操作："<<endl;
    cout<<"1：添加 2：删除 3：查询 4：排序 5:建立新文件"<<endl;
    int i;
    cin>>i;
    switch(i)
    {
    case 1:
        {
            ifstream infile("tongxunlu.dat",ios::in);
            if(! infile)
            {
                cerr<<"open error,请建立文件"<<endl;
                exit(1);
            }
            tongxunlu data[40];
            for(int b=0;b<40;b++)
            {
                infile>>data[b].num;
                infile>>data[b].name;
                infile>>data[b].address;
                infile>>data[b].tel;
                infile>>data[b].youbian;
                infile>>data[b].email;
            }
            insertdata();
        };break;
    case 2:deletdata();break;
    case 3:checkdata();break;
    case 4:resetdata();break;
    case 5:
        {
            ofstream outfile("tongxunlu.dat",ios::out);
            if(! outfile)
            {
                cerr<<"open error";                    
                exit(1);
            }
            tongxunlu data[40];
            for(int i=0;i<40;i++)
            {
                data[i].num=0;
                data[i].name="0";
                data[i].address="0";
                data[i].tel=0;
                data[i].youbian=0;
                data[i].email="0";
            }
            cout<<"文件建立完成"<<endl;
        };break;
    default:cout<<"error\n";
    }
    return 0;
}
//输入数据
void insertdata()
{
    ofstream outfile("tongxunlu.dat",ios::out);
    if(! outfile)
    {
        cerr<<"open error";                    
        exit(1);
    }
    int i;
    cout<<"请输入学生编号，当输入0时添加数据结束"<<endl;
    cin>>i;
    while(i!=0)
    {   
        data[i-1].num=i;
        cout<<"请输入学生姓名：";
        cin>>data[i-1].name;
        cout<<"请输入学生住址：";
        cin>>data[i-1].address;
        cout<<"请输入学生电话：";
        cin>>data[i-1].tel;
        cout<<"请输入学生邮编:";
        cin>>data[i-1].youbian;
        cout<<"请输入学生email:";
        cin>>data[i-1].email;
        cout<<"请输入下一个编号：";
        cin>>i;
    }
    for(int c=0;c<40;c++)
    {
        outfile<<data[c].num<<endl;
        outfile<<data[c].name<<endl;
        outfile<<data[c].address<<endl;
        outfile<<data[c].tel<<endl;
        outfile<<data[c].youbian<<endl;
        outfile<<data[c].email<<endl;
    }
    outfile.close();
    cout<<"数据输入完毕"<<endl;
}
//删除数据
void deletdata()
{
    ifstream infile("tongxunlu.dat",ios::in);
    if(!infile)
    {
        cerr<<"open error,请建立新文件"<<endl;
        exit(1);
    }
    tongxunlu data[40];
    for(int b=0;b<40;b++)
    {
        infile>>data[b].num;
        infile>>data[b].name;
        infile>>data[b].address;
        infile>>data[b].tel;
        infile>>data[b].youbian;
        infile>>data[b].email;
        cout<<data[b].num<<endl;
    }
    int i,j;
    string n;
    cout<<"请选择："<<endl<<"1:按编号删除 2：按姓名删除"<<endl;
    cin>>i;
    if(i==1)
    {
        cout<<"请输入学生编号:";
        cin>>j;
        cout<<endl;
        if(j==0) cout<<"无此学生编号"<<endl;
        else if(data[j-1].num==0) cout<<"无该学生信息"<<endl;
        else
        {
            data[j-1].num=0;
            cout<<"学生信息删除完毕"<<endl;
        }
    }
    if(i==2)
    {
        cout<<"请输入学生姓名：";
        cin>>n;
        cout<<endl;
        if(n=="0") cout<<"无该学生信息"<<endl;
        else if(n!="0")
        {
            for(int m=0;m<40;m++)
            {
                if(data[m].name=="0") continue;
                if(data[m].name==n)
                {
                    data[m].name="0";
                    cout<<"学生信息删除完毕"<<endl;
                    break;
                }
                else continue;
            }
        }
    }
    else cout<<"error\n";
    ofstream outfile("tongxunlu.dat",ios::out);
    if(! outfile)
    {
        cerr<<"open error";                    
        exit(1);
    }
    for(int c=0;c<40;c++)
    {
        outfile<<data[c].num;
        outfile<<data[c].name;
        outfile<<data[c].address;
        outfile<<data[c].tel;
        outfile<<data[c].youbian;
        outfile<<data[c].email;
    }
    outfile.close();
}
//查询数据
void checkdata()
{
    ifstream infile("tongxunlu.dat",ios::in);
    if(! infile)
    {
        cerr<<"open error,请建立新文件"<<endl;
        exit(1);
    }
    tongxunlu data[40];
    for(int b=0;b<40;b++)
    {
        infile>>data[b].num;
        infile>>data[b].name;
        infile>>data[b].address;
        infile>>data[b].tel;
        infile>>data[b].youbian;
        infile>>data[b].email;
        cout<<data[b].num<<endl;
    }
    int a;
    cout<<"请选择："<<endl<<"1：全部查询 2：按条件查询"<<endl;
    cin>>a;
    if(a==1)
    {
        for(int j=0;j<40;j++)
        {
            if(data[j].num==0) continue;
            else
            {
                cout<<setw(10)<<data[j].num;
                cout<<setw(10)<<data[j].name;
                cout<<setw(10)<<data[j].address;
                cout<<setw(10)<<data[j].tel;
                cout<<setw(10)<<data[j].youbian;
                cout<<setw(10)<<data[j].email<<endl;
            }
        }
        cout<<"数据输出完毕"<<endl;
    }
    else if(a==2)
    {
        int j;
        cout<<"请选择："<<endl<<"1:按编号查询 2：按姓名查询"<<endl;
        cin>>j;
        if(j==1)
        {
            int k;
            cout<<"请输入编号：";
            cin>>k;
            cout<<endl;
            if(data[k-1].num==0) cout<<"无此学生信息"<<endl;
            else
            {
                cout<<setw(40)<<data[k-1].num;
                cout<<setw(40)<<data[k-1].name;
                cout<<setw(40)<<data[k-1].address;
                cout<<setw(40)<<data[k-1].tel;
                cout<<setw(40)<<data[k-1].youbian;
                cout<<setw(40)<<data[k-1].email<<endl;
                cout<<"数据输出完毕"<<endl;
            }
        }
        else if(j==2)
        {
            string n;
            cout<<"请输入学生姓名：";
            cin>>n;
            cout<<endl;
            for(int l=0;l<40;l++)
            {
                if(data[l].num==0) continue;
                else if(data[l].name==n)
                {
                    cout<<setw(40)<<data[l].num;
                    cout<<setw(40)<<data[l].name[20];
                    cout<<setw(40)<<data[l].address;
                    cout<<setw(40)<<data[l].tel;
                    cout<<setw(40)<<data[l].youbian;
                    cout<<setw(40)<<data[l].email<<endl;
                    cout<<"数据输出完毕"<<endl;
                    break;
                }
                else continue;
            }
        }
        else cout<<"error\n";
    }
    else cout<<"error\n";
}
//数据排序
void resetdata()
{
    ifstream infile("tongxunlu.dat",ios::in);
    if(! infile)
    {
        cerr<<"open error"<<endl;
        exit(1);
    }
    tongxunlu data[40];
    for(int b=0;b<40;b++)
    {
        infile>>data[b].num;
        infile>>data[b].name;
        infile>>data[b].address;
        infile>>data[b].tel;
        infile>>data[b].youbian;
        infile>>data[b].email;
        cout<<data[b].num<<endl;
    }
    int i;
    cout<<"请选择："<<endl<<"1:按编号排序 2：按姓名排序"<<endl;
    cin>>i;
    if(i==1)
    {
        for(int j=0;j<40;j++)
        {
            if(data[j].num==0) continue;
            else
            {
                cout<<setw(40)<<data[j].num;
                cout<<setw(40)<<data[j].name;
                cout<<setw(40)<<data[j].address;
                cout<<setw(40)<<data[j].tel;
                cout<<setw(40)<<data[j].youbian;
                cout<<setw(40)<<data[j].email<<endl;
            }
        }
        cout<<"数据输出完毕"<<endl;   
    }
    else if(i==2)
    {
        tongxunlu temp;
        for(int a=0;a<39;i++)
        {
            for(int b=38;b>=a;b--)
            {
                if(data[b].name>data[b+1].name)
                {
                    temp=data[b+1];
                    data[b+1]=data[b];
                    data[b]=temp;
                }
            }
        }
        for(int c=0;c<40;c++)
        {
            if(data[c].name=="0") continue;
            else
            {
                cout<<setw(40)<<data[c].num;
                cout<<setw(40)<<data[c].name[20];
                cout<<setw(40)<<data[c].address;
                cout<<setw(40)<<data[c].tel;
                cout<<setw(40)<<data[c].youbian;
                cout<<setw(40)<<data[c].email<<endl;
            }
        }
        cout<<"数据输出完毕"<<endl;   
    }
    else cout<<"error\n";
}

嗯，是那个文件里的内容
字符串之间没有分隔符
文件里储存的数据是一个数据占一行的，int型数据都是0（除了前3个），字符串型数据都没有……

string不是基本数据类型，且流对象的读写最好不要操作文本与数据混合的文件。这种情况还是用一个整型数表示字符串长度，用指定长度的字符数组进行存取操作。这样的文件结构可靠稳定。

楼主能把 tongxunlu.dat 的内容发上来看看吗？

effafwaefasff wefaw

这……看不懂哎，string这东西老师也就交代一下，里面的具体内容完全不知道的说