将 find 与 vector<pair<int， int>>

Question

我遇到了以下问题：假设我有

pair<int, int> p(1,2)
vector<pair<int, int>> vec;

我想使用find来获得指向向量中元素p的迭代器

find(vec.begin(), vec.end(), p)

但它给了我错误

type 'std::__1::pair<int, int>' does not provide a call operator

我应该如何继续？

Answer 1

这是我使用过的，效果很好。

#include <iostream>
#include <vector>
#include <algorithm>
struct FindPair {
    FindPair (int first, int second)
    : m_first_value(first)
    , m_second_value(second) { }
    int m_first_value;
    int m_second_value;
    bool operator()
        ( const std::pair<int, int> &p ) {
            return (p.first == m_first_value && p.second == m_second_value);
    }
};

int main()
{
    std::vector< std::pair<int, int> > myVec;
    std::vector< std::pair<int, int> >::iterator it;
    myVec.push_back(std::make_pair(1,1));
    myVec.push_back(std::make_pair(1,2));
    it = std::find_if(myVec.begin(), myVec.end(), FindPair(1, 2));
    if (it != myVec.end())
    {
        // We Found it
        std::cout << "Matched Found on Current Iterator!" << std::endl;
        std::cout << "it.first: " << (*it).first << std::endl;
        std::cout << "it.second: " << (*it).second << std::endl;
    }
    else
    {
        std::cout << "Nothing Matched!" << std::endl;
    }
    return 0;
}

输出：

Matched Found on Current Iterator! 
it.first: 1 
it.second: 2