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Create a vector by specifying the size and initialize elements with a default value in C++ STL

C++ STL | vector creation by specify size and values: Here, we are going to learn how to create a vector by specifying the size and initialize the all values with a default value in C++ STL?
Submitted by IncludeHelp, on May 12, 2019

What is the vector?

Vector is a container in C++ STL, it is used to represent array and its size can be changed.

Create a vector by specifying the size

We can create a vector by specifying the size and we can also initialize all elements with a default value while declaring it.

Here is the syntax to create a vector by specifying the size,

    vector<type> vector_name(size, default_value);

Here,

type – is the datatype.
vector_name – is any use defined name to the vector.
size – is the initial size of the vector.
default_value – is the value to initialize all elements.

Example to create/declare vector by specifying the size

    vector::<int> v1(5, 10);

C++ STL program to create a vector by specifying the size

//C++ STL program to create a vector 
//by specifying the size
#include <iostream>
#include <vector>
using namespace std;

int main()
{
    //vector declaration with size and value
    vector<int> v1(5, 10);

    //printing the vector elements
    //using for each kind of loop
    cout << "Vector v1 elements are: ";
    for (int element : v1)
        cout << element << " ";
    cout << endl;

    //pushing the elements
    v1.push_back(10);
    v1.push_back(20);
    v1.push_back(30);
    v1.push_back(40);
    v1.push_back(50);

    //printing the vector elements
    //using for each kind of loop
    cout << "After pushing the elements\nVector v1 elements are: ";
    for (int element : v1)
        cout << element << " ";
    cout << endl;

    return 0;
}

Output

Vector v1 elements are: 10 10 10 10 10
After pushing the elements
Vector v1 elements are: 10 10 10 10 10 10 20 30 40 50