initializing vector in c++ code example

Example 1: initialize vector of vector c++

#include <iostream>
#include <vector>
 
#define M 3
#define N 4
 
int main()
{
  // specify default value to fill the vector elements
  int default_value = 1;
  // first initialize a vector of ints with given default value
  std::vector<int> v(N, default_value);
  // Use above vector to initialize the two-dimensional vector
  std::vector<std::vector<int>> matrix(M, v);
  
  return 0;
}

Example 2: 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 3: c++ initialize a vector

#include <bits/stdc++.h> 
#include <vector> 
using namespace std; 
  
int main() 
{ 
// This vector initializes with the values: 10, 20, and 30
  vector<int> vect{ 10, 20, 30 }; 

    return 0; 
}

Example 4: declare vectors c++

vector<int> vec;
//Creates an empty (size 0) vector
 

vector<int> vec(4);
//Creates a vector with 4 elements.

/*Each element is initialised to zero.
If this were a vector of strings, each
string would be empty. */

vector<int> vec(4, 42);

/*Creates a vector with 4 elements.
Each element is initialised to 42. */


vector<int> vec(4, 42);
vector<int> vec2(vec);

/*The second line creates a new vector, copying each element from the
vec into vec2. */

Example 5: c++ vector initialization

vector<int> a;                                       // empty vector of ints
vector<int> b (5, 10);                                // five ints with value 10
vector<int> c (b.begin(),b.end());                     // iterating through second
vector<int> d (c);                                   // copy of c

Example 6: how to initialize a vector in c++

std::vector<type> name;