Question

c++文件和重载输出符问题

#include<iostream>
#include<string>
#include<fstream>
#include<stdlib.h>
using namespace std;
class Cstudents
{
public:
int num;
char name[30];
char gender;
int age;
float match;
float pc;
float en;
float sum;
float average;
Cstudents()
{
num=0;
strcpy(name," ");
gender=' ';
age=0;
match=0;
pc=0;
en=0;
sum=0;
average=0;
}
friend istream& operator>>(istream&,Cstudents&);
friend ostream& operator>>(ostream&,Cstudents&);

};
istream& operator>>(istream& is,Cstudents& c)
{
is>>c.name>>c.gender>>c.age>>c.match>>c.pc>>c.en;
return is;
}
ostream& operator>>(ostream& os,Cstudents& c)
{
os<<c.num<<c.name<<c.gender<<c.age<<c.match<<c.pc<<c.en;
return os;
}
void main()
{
Cstudents stu[20];
ofstream fout;
ifstream fin;
int i=1,n,max=1;
fout.open("students.txt",ios::out|ios::binary);
if(!fout)
{
cout<<"错误";
exit(1);
}
cout<<"输入学号：(0号为结束输入)";
while(cin>>n&&0!=n)
{
stu[n].num=n;
cout<<"输入名字 性别 年龄 数学 计算机 外语";
cin>>stu[n];
if(n>max)max=n;
}
while(i<max+1)
{
fout.write((char*)&stu[i],sizeof(Cstudents));
i++;
}
fout.close();
fin.open("students.txt",ios::in|ios::binary);
if(!fin)
{
cout<<"错误";
exit(1);
}
cout<<"num\t"<<"name\t"<<"sex"<<"age\t"<<"match\t"<<"pc\t"<<"en\t";
i=1;
while(fin&&i<max)
{
fin.read((char*)&stu[i],sizeof(Cstudents));
cout<<stu[i];
i++;
}
fin.close();
}

1>------ 已启动生成: 项目: lzz, 配置: Debug Win32 ------
1>正在编译...
1>Cstudents.cpp
1>d:\课件\程序\lzz\lzz\cstudents.cpp(21) : warning C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
1> c:\program files\microsoft visual studio 9.0\vc\include\string.h(74) : 参见“strcpy”的声明错误提示：
1>d:\课件\程序\lzz\lzz\cstudents.cpp(81) : error C2679: 二进制“<<”: 没有找到接受“Cstudents”类型的右操作数的运算符(或没有可接受的转换)

Answer 1

流运算符的重载要以友元函数的形式，并且声明和定义要放在一起。
改成这样，孙庆就可以了
#include<iostream>
#include<string>
#include<fstream>
#include<stdlib.h>
using namespace std;
class Cstudents
{
public:
int num;
char name[30];
char gender;
int age;
float match;
float pc;
float en;
float sum;
float average;
Cstudents()
{
num=0;
strcpy(name," ");
gender=' ';
age=0;
match=0;
pc=0;
en=0;
sum=0;
average=0;
}
friend istream& operator>>(istream& is,Cstudents& c)
{
is>>c.name>>c.gender>>c.age>>c.match>>c.pc>>c.en;
return is;
}

friend ostream& operator<<(ostream& os,Cstudents& c)// <<符号也输错了
{
os<<c.num<<c.name<<c.gender<<c.age<<c.match<<c.pc<<c.en;
return os;
}

};
void main()
{
Cstudents stu[20];
ofstream fout;
ifstream fin;
int i=1,n,max=1;
fout.open("橘手students.txt",ios::out|ios::binary);
if(!fout)
{
cout<<"错误";
exit(1);
}
cout<<"输入学号：(0号为结束输入)";
while(cin>>n&&0!=n)
{
stu[n].num=n;
cout<<"输入圆凯嫌名字 性别 年龄 数学 计算机 外语";
cin>>stu[n];
if(n>max)max=n;
}
while(i<max+1)
{
fout.write((char*)&stu[i],sizeof(Cstudents));
i++;
}
fout.close();
fin.open("students.txt",ios::in|ios::binary);
if(!fin)
{
cout<<"错误";
exit(1);
}
cout<<"num\t"<<"name\t"<<"sex"<<"age\t"<<"match\t"<<"pc\t"<<"en\t";
i=1;
while(fin&&i<max)
{
fin.read((char*)&stu[i],sizeof(Cstudents));
cout<<stu[i];
i++;
}
fin.close();
}

Answer 2

第一个错误不是很明白，你试试这样
String str="";
strcpy(name,str);
第二个错含蠢误也不是很明白，因为没找到81行枯宏在谈败陪哪儿。