Set all elements of vector to 0 in C++

Given a vector of elements, the task is to set all elements to zero in C++.

When a vector is created, all its values are initialized to zero.

The following code will help you understand this:

#include<bits/stdc++.h>
using namespace std;
 
int main()
{
    
    vector<int> v(5);       // Creating a vector of size 5
 
 
    for (int i=0; i<v.size(); i++)      // Printing default values
       cout << v[i]<<" ";
}

Output:

0 0 0 0 0

But if we are given a vector containing some elements we can set those elements to zero by using different methods. For example,

Input: v={1, 2, 3, 4, 5}

Output: 0 0 0 0 0

Let’s see some ways of doing this:

1. Using for loop

In this method, we will use for loop for modifying the elements of the vector to zero. We will traverse the vector using the iterator i ranging from i=0 to i=v.size()-1(last element).

The following C++ code will illustrate this method:

#include<bits/stdc++.h>
using namespace std;
 
int main()
{
    
    vector<int> v={1, 2, 3, 4, 5};       // Creating a vector 
     
    cout<<"Original Vector:"<<endl;
    for (int i=0; i<v.size(); i++)
        {
            
            cout << v[i]<<" ";
        }     
cout<<endl;
cout<<"Modified Vector"<<endl;
    for (int i=0; i<v.size(); i++)
        {
            v[i]=0;
            cout <<v[i]<<" ";
        }                       
       
}

Output:

Original Vector:
1 2 3 4 5
Modified Vector
0 0 0 0 0

2. Using fill()

The fill() function can be used to assign a particular value to all the elements in the vector in the range begin() and end().

Syntax:

fill(v.begin(), v.end(), value);

#include<bits/stdc++.h>
using namespace std;
 
int main()
{
    
    vector<int> v={1, 2, 3, 4, 5};       // Creating a vector 
     
    cout<<"Original Vector:"<<endl;
    for (int i=0; i<v.size(); i++)
        {
            
            cout << v[i]<<" ";
        }     
cout<<endl;

fill(v.begin(), v.end(), 0);
cout<<"Modified Vector"<<endl;
    for (int i=0; i<v.size(); i++)
        {
            
            cout <<v[i]<<" ";
        }                       
       
}

Output:

Original Vector:
1 2 3 4 5
Modified Vector
0 0 0 0 0

Also read: How to convert a string to a vector of chars in C++