Count total number of duplicate elements in an array

Posted on Apr 24, 2020

C program to count total number of duplicate elements in an array.

Program

#include<stdio.h>
#include<conio.h>
#define MAX 50

void read_array(int a[MAX], int n)
{
    int i;
    for(i=0;i<n;i++)
    {
        printf("Element %d\t:",i+1);
        scanf("%d",&a[i]);
    }
}

int dup_ele(int a[MAX], int freq[MAX], int n)
{
    int i, j, count, count1;

    for(i=0;i<n;i++)
    {
        freq[i] = -1;
    }
    for(i=0;i<n;i++)
    {
        count = 1;
        for(j=i+1;j<n;j++)
        {
            if(a[i]==a[j])
            {
                count++;
                freq[j] = 0;;
            }
        }
        if(freq[i] != 0)
        {
            freq[i] = count;
        }
    }

    count1 = 0;
    for(i=0;i<n;i++)
    {
        if(freq[i] > 1)
        {
            count1++;
        }
    }
    return(count1);
}

void main()
{
    int arr[MAX], freq[MAX];
    int i, n, count;

    printf("Enter the number of elements in the array\t:");
    scanf("%d",&n);

    printf("Enter the elements of the array\n");
    read_array(arr, n);

    count = dup_ele(arr, freq, n);

    printf("\nTotal number of duplicate elements is\t:%d",count);

    getch();
}

Output

Enter the number of elements in the array       :7
Enter the elements of the array
Element 1       :12
Element 2       :21
Element 3       :12
Element 4       :36
Element 5       :54
Element 6       :36
Element 7       :54

Total number of duplicate elements is   :3