How to Replace All Occurrences of an Element in a Deque in C++?

In C++, we have a container called deque (short for double-ended queue) that allows the insertion and removal of elements from both ends. In this article, we will see how to replace all occurrences of a specific element in a deque in C++.

Example:

Input: 
myDeque = {10,20,30,40,20,60}
target = 30
new_element = 100

Output: 
Deque after Replacing: 10 20 100 40 100 60

Replacing All Occurrences of an Element in a Deque in C++

To replace all occurrences of a specific element in a std::deque in C++, we can use the std::replace() function that replaces all occurrences of a given target value in a range with another new value.

Syntax of std::replace

replace (first, last, target, new_value);

Here,

first: Iterator to the beginning of the range.
last: Iterator to the end of the range.
target: Value to be replaced.
new_value: New value to replace the target value.

C++ Program to Replace All Occurrences of a Specific Element in a Deque

The below example demonstrates how we can use the replace() function to replace all occurrences of a specific element in a deque in C++ STL.

C++

// C++ program to illustrate how to replace all occurrences
// of a specific element in a deque
#include <algorithm>
#include <deque>
#include <iostream>
using namespace std;

int main()
{
    // Creating a deque
    deque<int> myDeque = { 10, 20, 30, 40, 20, 60 };

    // traget value to be removed
    int target = 30;
    // new value to replace target value
    int new_element = 100;

    // Replacing all occurrences of 30 with 100
    replace(myDeque.begin(), myDeque.end(), target,
            new_element);

    // Printing the updated deque
    cout << "Updated deque is : ";
    for (int i : myDeque) {
        cout << i << " ";
    }
    cout << endl;

    return 0;
}