Question

alhorithm of prime number

Answer 1

In C:

#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;
}

Answer 2

#include<stdio.h>
int main()
{
    int n,i=2;
    printf("Enter a number:");
    scanf("%d",&n);
    while(n%i!=0)
    {
        i++;
    }
    if(i==n)    printf("%d is a prime number",n);
    else        printf("%d is a not prime number",n);
    return 0;
}

Answer 3

/* c programming*/
/* compute weather no. is prime or not */
/*YUVRAJ JWALA */
#include <stdio.h>
int main()
{
   int a,i,count=0;
   printf("write a number\n");
   scanf("%d",&a);
   for (i=1;i<=a;i++)
   {
       if (a%i==0)        /*THIS IS THE ALOGRITHM OF PRIME NUMBER*/
          count++;
   }
   (count>2)?printf("%d is not prime number",a):printf("%d is prime number",a);
   return 0;
}