C Exercises: Count the total number of duplicate elements in an array
C Array: Exercise-5 with Solution
Write a program in C to count the total number of duplicate elements in an array.
Visual Presentation:

Pseudo code to count the total number of duplicate elements in an array:
- Initialize a variable 'count' to 0.
- Read the array size, 'n'.
- Declare an integer array of size 'n'.
- Read the array elements.
- Loop through each element of the array from index 0 to n-2: a. Loop through the remaining elements of the array from index i+1 to n-1: i. If the current element and any of the remaining elements are equal, increment the 'count' variable and break out of the inner loop.
- Print the value of 'count' as the total number of duplicate elements in the array.
- End
Sample Solution:
C Code:
#include <stdio.h>
// Main function
int main()
{
int arr[100]; // Declare an array of size 100 to store integer values
int n, mm = 1, ctr = 0; // Declare variables to store array size, mm (unused), and duplicate counter
int i, j; // Declare loop counters
// Prompt the user to input the number of elements to be stored in the array
printf("Input the number of elements to be stored in the array :");
scanf("%d", &n);
// Prompt the user to input n elements into the array
printf("Input %d elements in the array :\n", n);
for (i = 0; i < n; i++)
{
printf("element - %d : ", i);
scanf("%d", &arr[i]); // Read the input and store it in the array
}
// Check for duplicate elements in the array using nested loops
for (i = 0; i < n; i++)
{
for (j = i + 1; j < n; j++)
{
if (arr[i] == arr[j])
{
ctr++; // Increment the duplicate counter if a duplicate is found
break; // Exit the inner loop as soon as a duplicate is found
}
}
}
// Display the total number of duplicate elements found in the array
printf("Total number of duplicate elements found in the array: %d\n", ctr);
return 0; // Return 0 to indicate successful execution
}
Sample Output:
Input the number of elements to be stored in the array :5 Input 5 elements in the array : element - 0 : 1 element - 1 : 1 element - 2 : 2 element - 3 : 3 element - 4 : 3 Total number of duplicate elements found in the array: 2
Flowchart:

C Programming Code Editor:
Previous: Write a program in C to copy the elements one array into another array.
Next: Write a program in C to print all unique elements in an array.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
- Weekly Trends
- Python Interview Questions and Answers: Comprehensive Guide
- Scala Exercises, Practice, Solution
- Kotlin Exercises practice with solution
- MongoDB Exercises, Practice, Solution
- SQL Exercises, Practice, Solution - JOINS
- Java Basic Programming Exercises
- SQL Subqueries
- Adventureworks Database Exercises
- C# Sharp Basic Exercises
- SQL COUNT() with distinct
- JavaScript String Exercises
- JavaScript HTML Form Validation
- Java Collection Exercises
- SQL COUNT() function
- SQL Inner Join