函数配接器

#include <iostream>
#include <vector>
#include <iterator>  
#include <algorithm>
#include <functional>
using namespace std;
class PlusNum :public binary_function<int,int,void>
{
public:
    void operator()(int &x,int y) const
    {
        x += y;
    }
};
void PlusInt(int x, int y)
{
    cout<< x + y<<" ";
}
int SubInt(int x, int y)
{
    return x-y;
}
int main()
{
    vector<int> vi = {1,4,6,2,5,7,9};
    //bind2nd将常数和函数子配接。常数100作为 PlusNum函数子中operator(x,y)的第二个参数 y
    for_each(vi.begin(),vi.end(),bind2nd(PlusNum(), 100) );    
    copy(vi.begin(),vi.end(),ostream_iterator<int>(cout," "));
    cout<<endl;
    
    //bind2nd将普通函数和函数子配接。函数 SubInt()的返回值作为 PlusNum函数子中operator(x,y)的第二个参数 y
    for_each(vi.begin(),vi.end(),bind2nd(PlusNum(), SubInt(1010,10)) );    
    copy(vi.begin(),vi.end(),ostream_iterator<int>(cout," "));
    cout<<endl;

    //用ptr_fun将一个函数适配成一个函数子，再用bind2nd将其与常数结合。
    for_each(vi.begin(),vi.end(),bind2nd(ptr_fun(PlusInt),1000) );        
    
    return 0;
}