C++ A prime number is an integer greater than 1 that is evenly divisible by only

Question

C++

A prime number is an integer greater than 1 that is evenly divisible by only 1 and itself. For example, the number 5 is prime because it can only be evenly divided by 1 and 5. The number 6, however is not prime because it can be divided by 1, 2, 3, and 6.

Write a Boolean function named isPrime, which takes an integer as an argument and returns true if the argument is a prime number, and false otherwise. Demonstrate the function in a complete program.

HINT: Review the functionality of the % (modulus) operator

Explanation / Answer

// C++ code
#include <iostream>

using namespace std;

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

   return true;
}

int main()
{
   int n;

   cout << "Enter a number: ";
   cin >> n;

   if(isPrime(n) == true)
       cout << n << " is Prime ";
   else
       cout << n << " is not Prime ";
}

/*
output:

Enter a number: 5
5 is Prime

Enter a number: 6
6 is not Prime

Enter a number: 11
11 is Prime

Enter a number: 15
15 is not Prime

*/

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