class Clock
{
public:
    Clock(int NH=0,int NM=0,int NS=0){H=NH;M=NM;S=NS;}
    void ST() {cout<<H<<":"<<M<<":"<<S<<endl;}    void operator++();
    void operator++(int);
private:
    int H,M,S;
};
请问void ST()(红色部分)为什么在类内定义时就是正确的,而在类外定义则出错?

class Clock
{
public:
    Clock(int NH=0,int NM=0,int NS=0){H=NH;M=NM;S=NS;}
    void ST(){cout<<H<<":"<<M<<":"<<S<<endl;}
    void operator++();
    void operator++(int);
private:
    int H,M,S;
};
抱歉,上面写的东西有点乱,我的意思是为什么void ST()这个成员函数在类内实现时程序就可运行,而有类外实现则出错.

不用麻烦各位了,我找到了问题的答案,是我自己的疏忽,谢谢曾关注过本帖的人

都正确

谢谢你的关注与答复,问题我已解决.我练习的主要是一个运算符重载的程序的一部分.
其实类外类内实现都可,只是出了一点小问题而已.完整代码如下.
#include "stdafx.h"
#include<iostream>
using namespace std;
class Clock
{public:
    Clock(int NH=0,int NM=0,int NS=0){H=NH;M=NM;S=NS;}
    void ST(){cout<<H<<":"<<M<<":"<<S<<endl;}    //ST表示ShowTime,这句可
    //在类外实现.void Clock::ST(){cout<<H<<":"<<M<<":"<<S<<endl;}   
         void operator++();                  
    void operator++(int);
private:
    int H,M,S;
};

//void ST()
//{cout<<H<<":"<<M<<":"<<S<<endl;}

void Clock::operator ++()
{S++;
  if(S>=60)
   {S=S-60;
    M++;
       if(M>=60)
       {M=M-60;
           H++;
           H=H%24;
       }
    }
cout<<"++Clock;";
}

void Clock::operator ++(int)
{S++;
  if(S>=60)
   {S=S-60;
    M++;
       if(M>=60)
       {M=M-60;
           H++;
           H=H%24;
       }
    }
cout<<"++Clock++;";
}

int _tmain(int argc, _TCHAR* argv[])
{Clock myClock(23,59,59);
cout<<"First time output:";
myClock.ST();
myClock++;
myClock.ST();
++myClock;
myClock.ST();
    return 0;
}