Delete prime numbers from an array

Posted on Apr 24, 2020

C program to delete prime numbers from 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]);
    }
}

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

int prime(int num)
{
    int i, flag;

    flag=0;
    for(i=2;i<num/2;i++)
    {
        if(num%i == 0)
        {
            flag = 1;
            break;
        }
    }
    if(flag==1)
        return 0;
    else
        return 1;
}

void delete(int a[MAX], int n)
{
    int i, j;

    for(i=0;i<n;i++)
    {
        if(prime(a[i]))
        {
            for(j=i;j<n;j++)
            {
                a[j] = a[j+1];
            }
            n=n-1;
            //decrease loop counter by 1, to check shifted element
            i--;
        }
    }

    printf("\nModified array is\n");
    print_array(a, n);
}

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

    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);

    delete(arr, n);

    getch();
}

Output

Enter the number of elements in the array       :8
Enter the elements of the array
Element 1       :12
Element 2       :23
Element 3       :25
Element 4       :56
Element 5       :45
Element 6       :11
Element 7       :7
Element 8       :58

Modified array is
Element 1       :12
Element 2       :25
Element 3       :56
Element 4       :45
Element 5       :58