Tutorialspoint.dev

Initialize a vector in C++ (5 different ways)

Following are different ways to create and initialize a vector in C++ STL

Initializing by one by one pushing values :

// CPP program to create an empty vector
// and one by one push values.
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    // Create an empty vector
    vector<int> vect; 
     
    vect.push_back(10);
    vect.push_back(20);
    vect.push_back(30);
  
    for (int x : vect)
        cout << x << " ";
  
    return 0;
}

Output:



10 20 30

Specifying size and initializing all values :

// CPP program to create an empty vector
// and one by one push values.
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    int n = 3;
  
    // Create a vector of size n with
    // all values as 10.
    vector<int> vect(n, 10);
  
    for (int x : vect)
        cout << x << " ";
  
    return 0;
}

Output:

10 10 10

Initializing like arrays :

// CPP program to initialize a vector like
// array.
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    vector<int> vect{ 10, 20, 30 };
  
    for (int x : vect)
        cout << x << " ";
  
    return 0;
}

Output:



10 20 30

Initializing from array :

// CPP program to initialize a vector from
// array.
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    int arr[] = { 10, 20, 30 };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    vector<int> vect(arr, arr + n);
  
    for (int x : vect)
        cout << x << " ";
  
    return 0;
}

Output:

10 20 30

Initializing from another vector :

// CPP program to initialize a vector from
// another vector.
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    vector<int> vect1{ 10, 20, 30 };
  
    vector<int> vect2(vect1.begin(), vect1.end());
  
    for (int x : vect2)
        cout << x << " ";
  
    return 0;
}

Output:

10 20 30

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



This article is attributed to GeeksforGeeks.org

You Might Also Like

leave a comment

code

0 Comments

load comments

Subscribe to Our Newsletter