Q:

# C program to delete prime numbers from an array

Given an array of integer elements and we have to remove prime numbers using C program.

Example:

```    Input:
Array elements are:
100, 200, 31, 13, 97, 10, 20, 11

Output:
Array elements after removing prime numbers:
100
200
10
20```

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## Program to remove prime numbers from an array using C program

``````#include <stdio.h>

//function to check number is prime or not
//function will return 1 if number is prime
int isPrime(int num)
{
int i; //loop counter
//it will be 1 when number is not prime
int flag=0;
//loop to check number is prime or not
//we will check, if number is divisible
//by any number from 2 to num/2, then it
//will not be prime
for(i=2; i<num/2; i++)
{
if(num%i ==0)
{
flag =1;
break;
}
}
//flag is 1, if number is not prime
if(flag==1)
return 0;
else
return 1;
}

int main()
{
int i,j; //loop counters
//declaring array with prime and not prime numbers
int arr[]={100, 200, 31, 13, 97, 10, 20, 11};
//calculate length of the array
int len = sizeof(arr)/sizeof(arr[0]);

//delete prime numbers
for(i=0; i<len; i++)
{
if(isPrime(arr[i]))
{
//number is prime, then shift other
//elements to the left
for(j=i; j<len; j++)
{
arr[j] = arr[j+1];
}
//decrease loop counter by 1,
//to check shifted element
i--;
//decrease the length
len--;
}
}

//print elements after removing prime numbers
printf("Array elements after removing prime numbers:\n");
for(i=0; i<len; i++)
printf("%3d\n",arr[i]);

printf("\n");

return 0;
}``````

Output

```Array elements after removing prime numbers:
100
200
10
20
```

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