c++ - 初始化多维向量

Question

如何初始化向量的向量？

下面的代码使我的应用程序崩溃。

#include <iostream>
#include <vector>

int main()
{
    std::vector< std::vector< unsigned short > > table;
    for(unsigned short a = 0; a < 13; a++){
        for(unsigned short b = 0; b < 4; b++){
            table[a][b] = 50;
        }
    }
}

Answer 1

这将创建一个大小为 4 的大小为 13 的向量，每个元素设置为 50。

using std::vector; // to make example shorter
vector<vector<unsigned short>> table(13, vector<unsigned short>(4, 50));

Answer 2

您需要先调整它的大小：

std::vector<std::vector<unsigned short > > table;
table.resize(13);
for(unsigned short a = 0; a < 13; a++){
    table[a].resize(4);
    for(unsigned short b = 0; b < 4; b++){
        table[a][b] = 50;
    }
}