How to Count the Number of Occurrences of a Value in an Array in C++?

In C++, an array is a data structure that stores the collection of the same type of data in a contiguous memory location. In this article, we will learn how to count the number of occurrences of a value in an array in C++.

Example:

Input: 
arr= {2, 4, 5 ,2 ,4 , 5, 2 , 3 ,8}
Target = 2

Output: 
Number of occurences of 2 are : 3

Count the Number of Occurrences in an Array in C++

To count the number of occurrences of a specific value in an array, we can use a simple for loop while looking for our target value. If the target value is found, we increment the counter variable. We do this till the whole array is scanned.

Approach

• Initialize a counter variable set to zero.
• Iterate through the array and check if the current element matches the target value.
• If it matches, increment the counter by one.
• Else continue to the next iteration.
• Repeat the process until all elements in the array have been checked.
• Finally, return the counter.

C++ Program to Count the Number of Occurrences of a Value in an Array

The below example demonstrates how we can count the total number of occurrences of a value in an array.

C++

// C++ Program to illustrate how to count the number of
// occurrences of a value in an array
#include <iostream>
using namespace std;

int main()
{

    // initializating an Array
    int arr[] = { 2, 4, 5, 2, 4, 5, 2, 3, 8 };

    // Calculating the size of the array
    int n = sizeof(arr) / sizeof(arr[0]);

    // Defining the target number to search for
    int target = 2;
    // Initialize a counter
    int counter = 0;

    // Loop through the array elements
    for (int i = 0; i < n; i++) {
        // Check if the current element equals the target
        // number
        if (arr[i] == target) {
            counter++;
        }
    }

    // Output the result
    cout << "Number " << target << " occurs " << counter
         << " times in the array.";

    return 0;
}

Output

Number 2 occurs 3 times in the array.

Time Complexity: O(n), here n is the number of elements in the array.
Auxilliary Space: O(1)