运算符的重载

运算符的重载

就是对已有的运算符重新进行定义，用来适应不同的数据类型

意义：为了实现类的多态性，提高编程效率

格式：类名 operator 运算符 （运算符）{ }

例子：时钟类实现++（前置和后置）

#ifndef _CCLOCK_H_
#fefine   _CCLOCK_H_

class CClock

{

public:
CClock(int hour,int minute,int sec)
~CClock();
CClock& operator++()//前置++,返回引用的原因是没引用时返回的不是原来的本体

CClock operator++(int n);//后置
void show();

private:
int m_hour;
int m_minute;
int m_sec;

}

CClock::CClock(int hour, int minute, int sec)
{
m_hour = hour;
m_minute = minute;
m_sec = sec;
}

CClock::~CClock()
{
}


CClock& CClock::operator++()
{
++m_sec;
if (m_sec == 60)
{
++m_minute;
m_sec = 0;
}
if (m_minute == 60)
{
++m_hour;
m_minute = 0;
}
if (m_hour == 24)
{
m_hour = 0;
}
return *this;
}

CClock CClock::operator++(int n)
{
CClock temp(*this);
m_sec++;
if (m_sec == 60)
{
m_minute++;
m_sec = 0;
}
if (m_minute == 60)
{
m_hour++;
m_minute = 0;
}
if (m_hour == 24)
{
m_hour = 0;
}
return temp;
}
void CClock::show()
{
if (m_hour < 10)
std::cout << "0" << m_hour<<":";
else
std::cout << m_hour<<":";
if (m_minute < 10)
std::cout << "0" << m_minute<<":";
else
std::cout << m_minute<<":";
if (m_sec < 10)
std::cout << "0" << m_sec;
else
std::cout << m_sec << std::endl;
}

#endif

注：特别的几个不能做重载符：sizeof，::，.，*，?:;

写个输入输出的重载：//注意：输入，输出符的重载必须用友元

#ifndef _CCLOCK_H_
#fefine   _CCLOCK_H_

class CA

{

friend istream& operator>>(istream& cin,CVactor& CTemp)

{

cin>>Temp;

return cin;

}
friend ostream& operator<<(ostream& cout, CVactor& CTemp)

{

cout<<Temp;

return cout;

}

   

}

欢迎指点