时间:2008-06-04 18:30:09   来源:论坛整理  作者:  编辑:chinaitzhe

可以向文件输出，但是读入的时候就会出现问题
不知道为什么~
还有教材讲打开文件会返回数值，而编译的时候报错：error C2120: 'void' illegal with all types 怎么改？
谢谢~

//教材《C 面向对象程序设计》清华大学出版社 谭浩强编著 第八章 习题3
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

const unsigned int N=7;//职员个数

struct employee//定义employee结构体
{
int num;
string name;
int age;
float wage;
};

employee emp[N];
int i;
int order=4;

ifstream ifile;//定义输入文件流ifile
ofstream ofile;//定义输出文件流ofile

void input()
{
employee temple;
cout < <"input information of employee:" < <endl;//输入T个职员的资料
cout < <"number:";
cin>>temple.num;
cout < <"name:";
cin>>temple.name;
cout < <"age:";
cin>>temple.age;
cout < <"wage:";
cin>>temple.wage;
cout < <endl;
ofile < <temple.num < <" " < <temple.name < <" " < <temple.age < <" " < <temple.wage < <endl;
}

void outputall(struct employee *e)
{for(i=0;i <N;i )//输出全部职员的资料
{
ifile>>e->num;
cout < <"number:" < <e->num < <" ";
ifile>>e->name;
cout < <"name:" < <e->name < <" ";
ifile>>e->age;
cout < <"age:" < <e->age < <" ";
ifile>>e->wage;
cout < <"wage:" < <e->wage < <endl;
e ;
}
cout < <endl;
}

void check(struct employee *e)
{
int num;
cout < <"input the employee's number:" < <endl;//输入职员号码(num)输出职员资料
cin>>num;
for(i=0;i <N;i )
{
if(e->num==num)
{
ifile>>e->num;
cout < <"number:" < <e->num < <" ";
ifile>>e->name;
cout < <"name:" < <e->name < <" ";
ifile>>e->age;
cout < <"age:" < <e->age < <" ";
ifile>>e->wage;
cout < <"wage:" < <e->wage < <endl;
goto out;
}
e ;
}
cerr < <"sorry! No." < <num < <" do not exist." < <endl;
out: ;
}

int main()
{
ifile.open("employee.txt",ios::in);
if(ifile.open("employee.txt",ios::in)==0)
{cerr < <"open employee.txt error!" < <endl;
exit(1);}
ofile.open("employee.txt",ios::out ¦ios::app);
if(ofile.open("employee.txt",ios::out ¦ios::app)==0)
{cerr < <"open employee.txt error!" < <endl;
exit(1);}

cout < <"welcome to the information of employee management system" < <endl;
cout < <"press 1 input information of employee" < <endl;
cout < <"press 2 look up the employee through the number" < <endl;
cout < <"press 3 output all tinformation" < <endl;
cout < <"press 0 quit" < <endl;
while(order!=0)
{
cout < <"order:";
cin>>order;
switch(order)
{
case 1: input(); break;
case 2: check(emp); break;
case 3: outputall(emp); break;
case 0: goto quit; break;
default: cerr < <"error!" < <endl;
}
}

quit:
ifile.close();
ofile.close();
return 0;
}

文件employee.txt
1 Adam 19 2000
2 Boa 19 5000
3 Cola 18 3000
4 David 23 2000
5 Eva 18 4000
网友回复:error C2120: 'void' illegal with all types

VC6.0中提示返回值为void

改为
if(!ifile.is_open())
{cerr < <"open employee.txt error!" < <endl;
exit(1);}
网友回复:ifile.open("employee.txt",ios::in);
if(ifile.open("employee.txt",ios::in)==0)
{cerr < <"open employee.txt error!" < <endl;
exit(1);}
ofile.open("employee.txt",ios::out |ios::app);
if(ofile.open("employee.txt",ios::out |ios::app)==0)
{cerr < <"open employee.txt error!" < <endl;
exit(1);}

这一段你要做什么啊？很希奇的写法。
fstream对象可以同时读写

这样的写法有问题
网友回复:帮你改了下：

C/C code

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#include <iostream> 

#include <fstream> 

#include <string> 

using namespace std; 



const unsigned int N=7;//职员个数 



struct employee//定义employee结构体 

{ 

    int num; 

    string name; 

    int age; 

    float wage; 

}; 



employee emp[N]; 

int i; 

int order=4; 



ifstream ifile;//定义输入文件流ifile 

ofstream ofile;//定义输出文件流ofile 



void input() 

{ 

employee temple; 

//ofstream ofile;

cout <<"input information of employee:" <<endl;//输入T个职员的资料 

cout <<"number:"; 

cin>>temple.num; 

cout <<"name:"; 

cin>>temple.name; 

cout <<"age:"; 

cin>>temple.age; 

cout <<"wage:"; 

cin>>temple.wage; 

cout <<endl; 

ofile <<temple.num <<" " <<temple.name <<" " <<temple.age <<" " <<temple.wage <<endl; 

} 



void outputall(struct employee *e) 

{

     //ifstream ifile;

     for(i=0;i <N;i  )//输出全部职员的资料 

{ 

ifile>>e->num; 

cout <<"number:" <<e->num <<" "; 

ifile>>e->name; 

cout <<"name:" <<e->name <<" "; 

ifile>>e->age; 

cout <<"age:" <<e->age <<" "; 

ifile>>e->wage; 

cout <<"wage:" <<e->wage <<endl; 

e  ; 

} 

cout <<endl; 

} 



void check(struct employee *e) 

{ 

    int num; 

    //ifstream ifile;

    

    

    cout <<"input the employee's number:" <<endl;//输入职员号码(num)输出职员资料 

cin>>num; 

for(i=0;i <N;i  ) 

{ 

if(e->num==num) 

{ 

ifile>>e->num; 

cout <<"number:" <<e->num <<" "; 

ifile>>e->name; 

cout <<"name:" <<e->name <<" "; 

ifile>>e->age; 

cout <<"age:" <<e->age <<" "; 

ifile>>e->wage; 

cout <<"wage:" <<e->wage <<endl; 

goto out; 

} 

e  ; 

} 

cerr <<"sorry! No." <<num <<" do not exist." <<endl; 

out: ; 

} 



int main() 

{ 

    //ifile.open("employee.txt",ios::in); 

    //ifstream ifile;

    //ofstream ofile;

    

    ifile.open("employee.txt");

    if(!ifile.is_open()) 

    {

        //cerr <<"open employee.txt error!" <<endl; 

        cout<<  "Could not open the file \n"<< endl;

        exit(1);

    } 

    

    ofile.open("employee.txt",ios::out|ios::app); 





    cout <<"welcome to the information of employee management system" <<endl; 

    cout <<"press 1 input information of employee" <<endl; 

    cout <<"press 2 look up the employee through the number" <<endl; 

    cout <<"press 3 output all tinformation" <<endl; 

    cout <<"press 0 quit" <<endl; 

    while(order!=0) 

    { 

        cout <<"order:"; 

        cin>>order; 

        switch(order) 

        { 

            case 1: input(); break; 

            case 2: check(emp); break; 

            case 3: outputall(emp); break; 

            case 0: goto quit; break; 

            default: cerr <<"error!" <<endl; 

        } 

    } 



    quit: 

    ifile.close(); 

    ofile.close(); 

    system("pause");

              

    return 0; 

} 

网友回复:最后一个小问题
在order:2的时候，输入职员号，输出职员信息，name:后面是空白的
是什么原因呢？是因为string不是内置类型？还是...