find_first_of用于在序列A中查找某个元素，该元素至少和序列B中的一个元素存在满足指定条件的情况。

#include <algorithm>
#include <iostream>
#include <string>
#include <vector>

using namespace std;

bool findComp(int i, int j) { return i == j; }
bool findComp2(int i, int j) { return i > j; }

int main()
{
    vector<int> v{ 1,2,2,2,4,5,2,3,4,7,8,9,1,7,2,3,4 };
    vector<int> d{ 5,2,3,4};

    auto it = find_first_of(v.begin(), v.end(), d.begin(), d.end());
    if (it != v.end())
        cout << "v[" << it - v.begin() << "]=" << *it << endl;

    it = find_first_of(v.begin(), v.end(), d.begin(), d.end(), findComp);
    if (it != v.end())
        cout << "v[" << it - v.begin() << "]=" << *it << endl;

    it = find_first_of(v.begin(), v.end(), d.begin(), d.end(), findComp2);
    if (it != v.end())
        cout << "v[" << it - v.begin() << "]=" << *it << endl;

    return 0;
}

输出结果：

v[1]=2
v[1]=2
v[4]=4