Aprime number is a number that is only evenly divisible by itself and 1. 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 evenly by 1, 2, 3, and 6. design a boolean function called isprime, that accepts an integer as an argument and returns true if the argument is a prime number, or false otherwise. use the function in a program that prompts the user to enter a number and then displays a message indicating whether the number is prime. the following modules should be written: getnumber, that accepts a ref to an integer, prompts the user to enter a number, and accepts that input isprime, that accepts an integer as an argument and returns true if the argument is a prime number, or false otherwise showprime, that accepts an integer as an argument , calls isprime, and displays a message indicating whether the number is prime the main module, that will call getnumber and showprime

// here is code in C++.

#include <bits/stdc++.h>

using namespace std;

// function to check prime

bool isPrime(int n)

{

   // if input is less than 1

  if(n<1)

      return false;

   // if input is 1,2 or 3

  else if (n == 1||n ==2 ||n==3)

  {

      return true;

  }

  // if input is greater than 3

  else

  {

      for(int i=2; i<n; i++)

      {

          if(n%i==0)

              return false;

      }

      return true;

  }

}

// driver function

int main()

{

   // variable

   int num;

  cout << "Enter a number: ";

  // read the input number

  cin >> num;

   // call function to check prime

  if (isPrime(num)==true)

  // if prime

      cout << num << " is prime.";

  else

  // if not prime

      cout << num << " is not prime.";

return 0;

}

Explanation:

Read a number from user and assign it to "num".Then call the function isPrime() with "num" as parameter.In this function, if the input is less than 1 then it will return "false".If input is 1 or 2 or 3 then it will return "true".For an input greater than 3, if the number is divisible by only 1 and itself then function will return "true" otherwise it will return "false".

Output:

Enter a number: 17

17 is prime.

answer; always; never;