vector in vector c++ code example

Example 1: how to create a vector in c++

// CPP program to create an empty vector 
// and push values one by one. 
#include <vector>

using namespace std;
int main() 
{ 
    // Create an empty vector 
    vector<int> vect;  
    //add/push an integer to the end of the vector
    vect.push_back(10); 
	//to traverse and print the vector from start to finish
    for (int x : vect) 
        cout << x << " ";

    return 0; 
}

Example 2: 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 3: vector in c++

vector<int> g1; 
  
    for (int i = 1; i <= 5; i++) 
        g1.push_back(i); 
  
    cout << "Output of begin and end: "; 
    for (auto i = g1.begin(); i != g1.end(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of cbegin and cend: "; 
    for (auto i = g1.cbegin(); i != g1.cend(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of rbegin and rend: "; 
    for (auto ir = g1.rbegin(); ir != g1.rend(); ++ir) 
        cout << *ir << " ";

Example 4: 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 5: 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.

Example 6: how to create a vector from elements of an existing vector in cpp

// Initializing vector with values 
    vector<int> vect1{1, 2, 3, 4}; 
  
    // Declaring another vector 
    vector<int> vect2; 
  
    // Copying vector by assign function 
    vect2.assign(vect1.begin(), vect1.end());