c++ - 如何在 map vector 内的 map 上使用 find()？

Question

我想访问 map vector 中的特定元素。我的代码如下:

#include <iostream>
#include <vector>
#include <map>

using namespace std;

int main() {
    std::vector<map <string, int> > vecOfMaps;
    map <string, int> myMap;

    for (int j = 0; j < 10; j++) {
        myMap["alpha"] = j;
        myMap["beta"] = j*2;
        vecOfMaps.push_back(myMap);
    }

    int start = 3;
    int end = 5;
    int counter = start;

    for (std::vector<map <string, int> >::iterator vecIter = vecOfMaps.begin()+start; vecIter != vecOfMaps.begin()+end; ++vecIter) {
        map<string, int>::iterator mapIter = vecIter.find("alpha");
        cout << "\n vecElement " << counter << " mapString " << mapIter->first << " mapInt " << mapIter->second;
        counter++;
    }
    return 0;
}

但是，这段代码给出了以下编译错误:

error: ‘std::vector, int> >::iterator’ has no member named ‘find’
map::iterator mapIter = vecIter.find("alpha");

如何在 map vector 中找到 map 内部的条目？

Answer 1

迭代器的作用类似于指向 vector 的指针，因此使用箭头，即间接表示法:

vecIter->find("alpha");