bind1st & bind2nd

#include <iostream>#include <functional>#include <algorithm>#include <vector>using namespace std;int main(){vector<int> coll;for(int i = 1; i <= 13; ++i){coll.push_back(i);}//查找元素值大于10的元素的个数//也就是使得10 < elem成立的元素个数int res = count_if(coll.begin(), coll.end(), bind1st(less<int>(), 10));cout<<"[10 < elem]: "<<res<<endl;//查找元素值小于10的元素的个数//也就是使得elem < 10成立的元素个数res = count_if(coll.begin(), coll.end(), bind2nd(less<int>(), 10));cout<<"[elem < 10]: "<<res<<endl;return 0;}/*Output:[10 < elem]: 3[elem < 10]: 9*/