C Program to Check Whether a Number is Prime or Not

@codevarsity
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A simple C program to check whether an integer (entered by the user) is a prime number or not using for loop and if..else statement.

Code

#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 nonprime number
        if(n%i==0)
        {
            flag=1;
            break;
        }
    }

    if (flag==0)
        printf("%d is a prime number.",n);
    else
        printf("%d is not a prime number.",n);
    
    return 0;
}

Output

Enter a positive integer: 29
29 is a prime number.

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