c++ 对符合条件的元素进行计数（count_if）

#include <iostream>     // cout
#include <algorithm>    // count_if
#include <vector>       // vector
using namespace std;
bool IsOdd (int i) { return ((i%2)!=0); }

int main () {
    vector<int> myvector;
    for (int i=1; i<10; i++) myvector.push_back(i); // myvector: 1 2 3 4 5 6 7 8 9
    
    int mycount = count_if (myvector.begin(), myvector.end(), IsOdd);
    cout << "myvector contains " << mycount  << " odd values.\n";
    
    return 0;
}