CPP

how to make a 2d vector in c++

// Create a vector containing n 
//vectors of size m, all u=initialized with 0
vector<vector<int> > vec( n , vector<int> (m, 0));  

2d vector cpp

For user defined size:

vector<vector<int>> vec( n ); 
where n -> number of rows

vector<vector<int>> vec( n , vector<int> (m, 0)); 
where n -> number of rows
where m -> number of columns (all initialized with 0)
  

2D vector in cpp

// CPP program
#include <iostream>
#include <vector>
using namespace std;
int main()
{
    int n = 3;
    int m = 4;
  
    /*
    We create a 2D vector containing "n"
    elements each having the value "vector<int> (m, 0)".
    "vector<int> (m, 0)" means a vector having "m"
    elements each of value "0".
    Here these elements are vectors.
    */
    vector<vector<int>> vec( n , vector<int> (m, 0)); 
  
    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < m; j++)
        {
            cout << vec[i][j] << " ";
        }
        cout<< endl;
    }
      
    return 0;
}

2D vector in cpp

// CPP program
#include <iostream>
#include <vector>
using namespace std;
int main()
{
    int n = 3;
    int m = 4;
  
    /*
    We create a 2D vector containing "n"
    elements each having the value "vector<int> (m, 0)".
    "vector<int> (m, 0)" means a vector having "m"
    elements each of value "0".
    Here these elements are vectors.
    */
    vector<vector<int>> vec( n , vector<int> (m, 0)); 
  
    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < m; j++)
        {
            cout << vec[i][j] << " ";
        }
        cout<< endl;
    }
      
    return 0;
}