c++的operator操作符
#include <iostream>
using namespace std;
class A
{
public:
A(double _data = 0.0):data(_data){}
A& operator = (const A& rhs)
{
data = rhs.data;
return *this;
}
A& operator += (const double rhs)
{
data = data + rhs;
return *this ;
}
A& operator += (const A& rhs)
{
data = data + rhs.data;
return *this ;
}
friend A operator + (const A& lhs,const A& rhs);
friend A operator - (const A& lhs,const A& rhs);
friend A operator * (const A& lhs,const A& rhs);
friend A operator + (const A& lhs,double rhs);
friend A operator + (double lhs,const A& rhs);
friend A operator * (const A& lhs,double rhs);
friend A operator * (double lhs,const A& rhs);
friend A operator - (const A& lhs,double rhs);
friend A operator - (double lhs,const A& rhs);
friend ostream& operator << (ostream& fout,A& a);
// A& operator -= (const double rhs);
// A& operator *= (const double rhs);
private:
double data;
};
A operator + (const A& lhs,const A& rhs)
{
A res(0);
res.data = lhs.data + rhs.data;
return res;
}
A operator - (const A& lhs,const A& rhs)
{
A res(0);
res.data = lhs.data - rhs.data;
return res;
}
A operator * (const A& lhs,const A& rhs)
{
A res(0);
res.data = lhs.data * rhs.data;
return res;
}
A operator + (const A& lhs,double rhs)
{
A res(0);
res.data = lhs.data + rhs;
return res;
}
A operator + (double lhs,const A& rhs)
{
A res(0);
res.data = lhs + rhs.data;
return res;
}
A operator * (const A& lhs,double rhs)
{
A res(0);
res.data = lhs.data * rhs;
return res;
}
A operator * (double lhs,const A& rhs)
{
A res(0);
res.data = lhs * rhs.data;
return res;
}
A operator - (const A& lhs,double rhs)
{
A res(0);
res.data = lhs.data - rhs;
return res;
}
A operator - (double lhs,const A& rhs)
{
A res(0);
res.data = lhs - rhs.data;
return res;
}
ostream& operator << (ostream& fout,A& a)
{
fout << a.data ;
return fout;
}
int main(int argc, char* argv[])
{
A a(3.4);
A b(1.2);
A d(5.6);
A c;
c = a + b + d;
cout << c << endl;
c=a+b;
cout << c << endl;
c=a+1.0;
cout << c << endl;
c=a-b;
cout << c << endl;
c=a-1.0;
cout << c << endl;
c=a*b;
cout << c << endl;
c=a*1.0;
cout << c << endl;
c=1.0+2.0*a*a-3.0*a*b;
cout << c << endl;
c += 1;
cout << c << endl;
c += a;
cout << c << endl;
return 0;
}http://www.apull.net/html/20130512144807.html
