Question

关于C++构造函数的定义问题！

#include<iostream.h>
class A
{public:
A();
A(int y,int m,int d)
{year=y;month=m;day=d;
cout<<year<<"/"<<month<<"/"<<day<<endl;
}
private:
int year;
int month;
int day;
}

main()
{A a(1990,2,19);
}

A(int y,int m,int d)这个构造函数在内部定义可以得出结果
但如果把程序改成
#include<iostream.h>
class A
{public:
A();
A(int y,int m,int d);

private:
int year;
int month;
int day;
}
A::A(int y,int m,int d)
{year=y;month=m;day=d;
cout<<year<<"/"<<month<<"/"<<day<<endl;
}
void main()
{A a(1990,2,19);
}
A(int y,int m,int d);在类外定义 程序报错 求解释 哪出毛病啊？

Answer 1

我改了一下，如下
#include<iostream>
using namespace std;
class A{
public:
A();
A(int y,int m,int d);
private:
int year;
int month;
int day;
};//注意，类定义后要加分号

A::A(int y,int m,int d){
year=y;month=m;day=d;
cout<<year<<"/"<<month<<"/"<<day<<endl;
}
void main(){
A a(1990,2,19);
return ;
}

Answer 2

类定义后面需要加分号