C Code for Prime Number

A prime number is a natural number greater than 1 which is not divisible by any other smaller natural number. In simple terms a prime number has only two positive divisors 1 and itself for example 2,3,5,7—– are prime numbers. Natural numbers other than prime numbers are known as composite numbers.

C Code for Prime Number

Lets see the C code for prime number. There are many different ways to write a C program to check whether a given number is a prime number or not. The simplest approach for checking prime numbers is to use a loop to iterate through all the numbers from 2 to the square root of the number. If any of those numbers divide the given number then the given number is not a prime number. Otherwise, it is a prime number.

#include <stdio.h>
#include <stdbool.h>

bool isPrime(int n)
{
    if (n < 2)
    {
        return false;
    }
    else
    {
        for (int i = 2; i * i <= n; i++)
        {
            if (n % i == 0)
                return false;
        }
        return true;
    }
}

void main()
{
    int number;
    printf("enter the number ");
    scanf("%d", &number);
    if (isPrime(number))
    {
        printf("Prime number");
    }
    else
    {
        printf("Not prime number");
    }
}

Output

See Also

• Hello World in C