Write a C program count total number of duplicate elements in an array

What is an Array ?

Arrays a kind of data structure that can store a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

Instead of declaring individual variables, such as number0, number1, …, and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and …, numbers[99] to represent individual variables. A specific element in an array is accessed by an index.

All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.

Here is source code of the C program count total number of duplicate elements in an array. The C program is successfully compiled and run(on Codeblocks) on a Windows system. The program output is also shown in below.

SOURCE CODE : :

/*  C program count total number of duplicate elements in an array */

#include <stdio.h>

int main()
{
    int arr[100];
    int i,j, n, count = 0;

    /*
     * Reads size and elements of array
     */
    printf("Enter size of the array : ");
    scanf("%d", &n);

    printf("\nEnter elements in array : \n");
    for(i=0; i<n; i++)
    {
        printf("\nEnter %d element in array : ",i+1);
        scanf("%d", &arr[i]);
    }

    /*
     * Finds all duplicate elements in array
     */
    for(i=0; i<n; i++)
    {
        for(j=i+1; j<n; j++)
        {
            /* If duplicate found then increment count by 1 */
            if(arr[i]==arr[j])
            {
                count++;
                break;
            }
        }
    }

    printf("\nTotal number of duplicate elements found in array = %d", count);

    return 0;
}

OUTPUT : :

Enter size of the array : 8

Enter elements in array :

Enter 1 element in array : 1

Enter 2 element in array : 2

Enter 3 element in array : 3

Enter 4 element in array : 2

Enter 5 element in array : 2

Enter 6 element in array : 1

Enter 7 element in array : 1

Enter 8 element in array : 3

Total number of duplicate elements found in array = 5