prime number program in c code example

Example 1: prime numbers in c

#include<stdio.h>
main() {
    int n, i, count=0;
    printf("Enter Number");
    scanf("%d",&n);
   
    for ( i = 1; i<= n; i++) {
        if (n % i == 1) {
            count++;
        }
    }
    if( count == 2) {
        printf("Prime Number");
    }
    else {
        printf("Not A  Prime Number");
    }
}

Example 2: prime number c program

int isPrime(int n) {
  for (int i = 2; i < n; i++) if (n % i == 0) return 0; 
  return 1;
}

Example 3: c program to check prime number using for loop

#include <stdio.h>
int main() {
    int n, i, flag = 0;
    printf("Enter a positive integer: ");
    scanf("%d", &n);

    for (i = 2; i <= n / 2; ++i) {

        // condition for non-prime
        if (n % i == 0) {
            flag = 1;
            break;
        }
    }

    if (n == 1) {
        printf("1 is neither prime nor composite.");
    }
    else {
        if (flag == 0)
            printf("%d is a prime number.", n);
        else
            printf("%d is not a prime number.", n);
    }

    return 0;
}

Example 4: prime number c

#include <stdio.h>
int main()
{
   int i, num, p = 0;
   printf("Please enter a number: \n");
   scanf("%d", &num);
   for(i=1; i<=num; i++)
   {
      if(num%i==0)
      {
         p++;
      }
   }
   if(p==2)
   {
      printf("Entered number is %d "\
             "and it is a prime number.",num);
   }
   else
   {
      printf("Entered number is %d "\
             "and it is not a prime number.",num);
   }
}

Example 5: c program array prime number

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