Prime Number Checker using C

Problem Statement

In this program we will code a basic program to check whether a given number is prime or not

Code

#include

using namespace std;

bool prime(int n)

{

 int count=0;

 int i;   

 for(i=2;i<=n/2;i++)

 {

 if(n%i==0)

 {            

   count=1;

 }                           

 }

 if(count==0)

 {

   return true;

 }

  return false;

}

int main()

{

  int n;

  printf("ENTER THE NUMBER : ");

  scanf("%d",&n);

  if(prime(n))

  {

    printf("PRIME NUMBER");

  }

  else

  {

    printf("NOT A PRIME NUMBER");

  }

  return 0;

}

Output

ENTER THE NUMBER : 7

PRIME NUMBER 

Explanation 

In this problem we have to check whether a given number is prime or not. A prime number is a whole number greater than 1 whose only factors are 1 and itself. A factor is a whole numbers that can be divided evenly into another number. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29.

For checking a prime number,we ran a for loop from i:2 to n/2,now if our number gets divided by any value of 'i' we set our counter to 1. After the end of the loop , if counter=0 then our number is a prime number else not.