vector of vectors c++ code example

Example 1: get values from a vector of vectors c++

#include <iostream>
#include <vector>
using namespace std;  

int main()
{
    vector<vector<int> > buff;

    for(int i = 0; i < 10; i++)
    {
        vector<int> temp; // create an array, don't work directly on buff yet.
        for(int j = 0; j < 10; j++)
            temp.push_back(i); 
 
        buff.push_back(temp); // Store the array in the buffer
    }

    for(int i = 0; i < buff.size(); ++i)
    {
        for(int j = 0; j < buff[i].size(); ++j)
            cout << buff[i][j];
        cout << endl;
    }

    return 0;
}

Example 2: c++ 2D vectors

int main() 
{ 
    int row = 5; // size of row 
    int colom[] = { 5, 3, 4, 2, 1 }; 
  
    vector<vector<int> > vec(row);  // Create a vector of vector with size equal to row. 
  	for (int i = 0; i < row; i++) { 
  		int col;  
        col = colom[i]; 
  		vec[i] = vector<int>(col); //Assigning the coloumn size of vector
        for (int j = 0; j < col; j++) 
            vec[i][j] = j + 1; 
    } 
  
    for (int i = 0; i < row; i++) { 
        for (int j = 0; j < vec[i].size(); j++) 
            cout << vec[i][j] << " "; 
        cout << endl; 
    } 
}

Example 3: how to use vectors c++

#include <iostream>
#include <vector>
using namespace std;

int main() {
  //vector element size
  const int size = 4; 
  //vector with int data type
  //all elements are equal to 4
  vector<int> myVect (size, 4);

  for (int i=0; i<size; i++) {
    cout << "Vector index(" << i <<") is: "<< myVect[i] << endl; 
  }
  return 0;
}

Example 4: vector of vectors c++

vector<vector<data_type>> vec;

Example 5: vector of vectors c++

#include <iostream> 
#include <vector> 
using namespace std; 
  
int main() 
{ 
	int n = 5;
	int m = 7;
	//Create a vector containing n vectors of size m and initalize them to 0.
	vector<vector<int>> vec(n, vector<int>(m, 0));

	for (int i = 0; i < vec.size(); i++) //print them out
	{
		for (int j = 0; j < vec[i].size(); j++)
		{
			cout << vec[i][j] << " ";
		}
		cout << endl;
	}
}

Example 6: vector of vectors c++

vector<vector<int>> matrix(x, vector<int>(y));

This creates a vector of x size y vectors, filled with 0's.