关系运算符仿函数

STL内建的“关系运算符仿函数”支持了等于，不等于，大于，大于等于，小于，小于等于六中运算。每一种都是二元运算

template<class T>
struct equal_to:public binary_function<T,T,bool>
{
	bool operator()(const T&x,const T& y)const {return x==y;};
}
template<class T>
struct not_equal_to:public binary_function<T,T,bool>
{
	bool operator()(const T& x,const T& y)const {return x!=y;}
};
template<class T>
struct greater:public binary_function<T,T,bool>
{
	bool operator()(const T&x ,const T7 y)const {return x>y;}
};
template<class T>
struct less:public binary_function<T,T,bool>
{
	bool operator()(const T&x ,const T7 y)const {return x<y;}
};
template<class T>
struct greater_equal:public binary_function<T,T,bool>
{
	bool operator()(const T&x ,const T7 y)const {return x>=y;}
};
template<class T>
struct less_equal:public binary_function<T,T,bool>
{
	bool operator()(const T&x ,const T7 y)const {return x<=y;}
};