STL中的ptr_fun

STL中的ptr_fun

       ptr_fun只是将一个普通的函数（或者函数指针）适配成类pointer_to_binary_function，而该类实际上是binary_function的子类，这样出来的functor就有利于同STL的算法等适配。 
      下面的例子就是说明了使用ptr_fun将普通的函数适配成bind1st或bind2nd能够使用的functor，否则对bind1st或bind2nd直接绑定普通函数，则编译出错。 

#include <algorithm>#include <functional>#include <iostream>using namespace std;int sum(int arg1, int arg2){cout<<"ARG 1: "<<arg1<<endl;cout<<"ARG 2: "<<arg2<<endl;int sum = arg1 + arg2;cout<<"SUM: "<<sum<<endl;return sum;}int main(int argc,char* argv[]){bind1st(ptr_fun(sum),1)(2); // the same as sum(1,2)bind2nd(ptr_fun(sum),1)(2); //the same as sum(2,1)getchar();return 0;}

运行结果：