单目运算符重载格式
++a和a++通过形参确定

data1  operator++()
{++this->a;return *this;
}data1  operator++(int)
{data1 temp=*this;this->a++;return temp;
}

举例使用单目运算符重载

#include "iostream"using namespace std;class data1
{public :int a;data1(int a):a(a){}  data1  operator++()
{++this->a;return *this;
}data1  operator++(int)
{data1 temp=*this;this->a++;return temp;
}};class data2
{public :int a;data2(int a):a(a){}  
};int main()
{data1 a(20);data1 b=a++;cout << b.a << endl;}