如何使用stl :: map作为二维数组 [英] how to use stl::map as two dimension array

问题描述

您能告诉我们如何使用stl：map作为二维数组吗？我想访问像mymap [i] [j]这样的个别元素，我不知道i或j的值是什么。

Could you let us know how to use stl:map as two dimension array? I wanted to access the individual elements as like mymap[i][j] where I do not know beforehand what the value of i or j could be. Any better ideas to do the same thing in other way?

推荐答案

你可以做

std::map<int, std::map<int, int> > mymap;

例如：

#include <map>
#include <iostream>

int main() 
{
    std::map<int, std::map<int, int> > mymap;

    mymap[9][2] = 7;
    std::cout << mymap[9][2] << std::endl;

    if (mymap.find(9) != mymap.end() && mymap[9].find(2) != mymap[9].end()) {
        std::cout << "My map contains a value for [9][2]" << std::endl;
    } else {
        std::cout << "My map does not contain a value for [9][2]" << std::endl;
    }

    return 0;
}

在标准输出中打印7，其后是我的地图包含[9] [2]。

prints 7 on the standard output, followed by "My map contains a value for [9][2]".

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