Question

我用c++语言来做文件操作，例如写入和读出的操作，但是当输入完数据之后，就进入死循环了，请各位高手帮忙

#include "stdafx.h"
#include<fstream.h>
#include"iostream.h"
#include"stdlib.h"

void enter(char *filename)
{
char name[30],flag='y';
int number,score;
ofstream outstuf;
outstuf.open(filename,ios::out);
if(!outstuf)
{cerr<<"file could not be open"<<endl;
abort();
}
outstuf<<"this is a file of students\n";
cout<<"请输入： number ,name ,an score: (enter Ctrl+z to end intput)\n";
while (cin>>number>>name>>score)
{
outstuf<<number<<'\t'<<name<<'\t'<<score<<'\n';
}
outstuf.close();
}

void display(char*filename)
{
char name[30];
int number,score;
ifstream instuf(filename,ios::in);
if(!instuf)
{cerr<<"file could not be open"<<endl;
abort();
}
char s[80];
instuf.getline(s,80);
while(instuf>>number>>name>>score)
{cout<<number<<'\t'<<name<<'\t'<<score<<'\n';
}
instuf.close();

}

void interfaced(void)
{
cout<<"文件复习:\n";
cout<<"=======================================\n";
cout<<" 输入纪录-----------------0\n";
cout<<" 查询纪录-----------------1\n";
cout<<" 退出---------------------2\n";
cout<<"=======================================\n";
cout<<"请输入数字(0--2):\n";
}

void main()
{
for(;;)
{
char filename[30];
int i;
cout<<"please input the name of student`s file"<<endl;
cin>>filename;
interfaced();
cin>>i;
switch(i)
{
case 0:
enter(filename);
break;
case 1:
display(filename);
break;
case 2:
exit(0);
default :
cout<<"警告!!!请输入数字0-2!\n";
)
}
}
}
问题补充：我用for语句主要是想当把数据输入完之后，再回到主界面，然后继续其他操作，如:显示操作,如果不用for我就不用在这问这问题了，因为我也试过，不用for就直接输入完数据就结束了。 //我用的环境是VC6.0。//“i”不是定义为整型数据吗？会变成ASCII的50？//

Answer 1

自问自答，正解为：
#include "stdafx.h"

#include<fstream.h>

#include"iostream.h"

#include"stdlib.h"

void enter(char *filename,int n)

{ char name[30],flag='y';

int number,score;

ofstream outstuf;

outstuf.open(filename,ios::out);

if(!outstuf) {cerr<<"file could not be open"<<endl; abort(); }

outstuf<<"this is a file of students\n";

cout<<"请输入： number ,name ,an score: (enter Ctrl+z to end intput)\n";
int i=n;
do
{i--; cin>>number>>name>>score;
outstuf<<number<<'\t'<<name<<'\t'<<score<<'\n';
}while(i!=0);
outstuf.close(); }

void display(char*filename)

{ char name[30]; int number,score;

ifstream instuf(filename,ios::in);

if(!instuf) {cerr<<"file could not be open"<<endl; abort(); }

char s[80]; instuf.getline(s,80);

while(instuf>>number>>name>>score)

{cout<<number<<'\t'<<name<<'\t'<<score<<'\n'; }

instuf.close();}

void interfaced(void){ cout<<"文件复习:\n"; cout<<"=======================================\n";

cout<<" 输入纪录-----------------0\n";

cout<<" 查询纪录-----------------1\n";

cout<<" 退出---------------------2\n";

cout<<"=======================================\n";

cout<<"请输入数字(0--2):\n";}

void main()

{

char filename[30]; int i,n;

cout<<"please input the name of student`s file"<<endl;

cin>>filename;
do
{j:interfaced();
i=NULL;
cin>>i;
if(i!=0&&i!=1&&i!=2)
{cout<<"please enter a right number!!!";
goto j;}
else
switch(i)
{
case 0: cout<<"输入多少个人的数据呢？"<<endl;
cin>>n;enter(filename,n);i=NULL;goto j;

case 1: display(filename);i=NULL;goto j;

case 2: exit(0);

default : cout<<"警告!!!请输入数字0-2!\n";i=NULL; goto j;

}
}while(i!=2&&i!='2');
}