[C/C++]_[操作符重载operator type()和operator()的区别]

标签：类型转换操作符   type   conversion   operator   中括号   

场景:

1.看到WTL的CWindow源码时会发现这样的operator重载，仔细看会发现它并不是重载()操作符.

	operator HWND() const throw()
	{
		return m_hWnd;
	}

如果重载（）操作符，应该是,返回值HWND应该在operator的左边，而且应该有两个括号()

HWND operator ()() const throw()
{
	return m_hWnd;
}

函数原型:

operator Type()

测试代码:

#include <iostream>
#include <string>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

using namespace std;

class Total
{
public:
	Total(float sum,float discount)
	{
		sum_ = sum;
		discount_ = discount;
	}
	~Total(){}

	operator float()
	{
		return sum_* discount_;
	}

	operator std::string()
	{
		char str[128];
		sprintf(str,"%f",sum_* discount_);
		return std::string(str);
	}

	float operator()()
	{
		return sum_* discount_;
	}
	float sum_;
	float discount_;
};

int main(int argc, char const *argv[])
{
	Total to(89,0.8);
	cout << to << endl;
	cout << to() << endl;
	cout << (std::string)to << endl;
	//cout << to(0.9) << endl;
	return 0;
}

71.2
71.2
71.200001

[C/C++]_[操作符重载operator type()和operator()的区别]

标签：类型转换操作符   type   conversion   operator   中括号   

原文地址：http://blog.csdn.net/infoworld/article/details/38901127