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# C program to check prime numbers in an array

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

Example:

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

Output:
100 - Not Prime
200 - Not Prime
31 - Prime
13 - Prime
97 - Prime
10 - Not Prime
20 - Not Prime
11 - Prime```

## Program to check prime numbers in 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 loop; //loop counter
//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);

//print array elements with message
//"prime" or "Not prime"
for(loop=0; loop<len; loop++)
{
printf("%3d - %s\n",arr[loop],(isPrime(arr[loop])?"Prime":"Not Prime"));
}

printf("\n");

return 0;
}``````

Output

```100 - Not Prime
200 - Not Prime
31 - Prime
13 - Prime
97 - Prime
10 - Not Prime
20 - Not Prime
11 - Prime```