#include<bits/stdc++.h>
using namespace std;

int main(){


vector< vector<int> > array;
    for (int i = 0; i < 5; i++)
    {
        array.push_back(vector<int>());//不断往array里加行 
    }
    for (int i = 0; i < array.size(); i++)//行 
    {
        for (int j = 0; j < 5; j++)//添加5列 
        {
            array[i].push_back(i + j);
        }
    }
    for (int i = 0; i < array.size(); i++)
    {
        for (int j = 0; j < 5; j++)
        {
            cout << array[i][j] << " ";//使用下标访问 
        }
        cout << endl;
    }
    return 0;
}

初始化

第一种

#include<bits/stdc++.h>
using namespace std;

int main(){
    int n;
    cin >> n;

    vector< vector<int> > a(n, vector<int>(2*n, 0));

    for(int i = 0; i < n ; i ++){
        for(int j = 0; j < 2 * n; j ++) cout << a[i][j] <<" ";
        cout << endl;
    }

       return 0;

}

第二种

#include<bits/stdc++.h>
using namespace std;

int main(){
    int n;
    cin >> n;

    vector<vector<int> >vv;  
      for(int c = 1; c <= n; c++)  
      vv.push_back(vector<int>(n,0));

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            cout << vv[i][j] << " ";
        }
        cout << endl;
    }
       return 0;

}