Exercise:
Write a C++ program to check for prime numbers using user-defined functions.
Click Here to View the Solution:
#include <iostream>
using namespace std;
int TestPrimeNumber(int);
int main()
{
int num1, num2;
bool check;
cout << "Insert the initial and final interval of the prime numbers:\n";
cin >> num1 >> num2;
// swapping n1 and n2 if n1 is greater than n2
if (num1 > num2)
{
num2 = num1 + num2;
num1 = num2 - num1;
num2 = num2 - num1;
}
cout << "Prime numbers between " << num1 << " and " << num2 << " are: ";
for(int x = num1+1; x < num2; ++x)
{
// If x is a prime number, check will be equal to 1
check = TestPrimeNumber(x);
if(check)
cout << x << " ";
}
return 0;
}
// user-defined function to check prime number
int TestPrimeNumber(int t)
{
bool Prime = true;
// 0 and 1 are not prime numbers
if (t == 0 || t == 1)
{
Prime = false;
}
else
{
for(int y = 2; y <= t/2; ++y)
{
if (t%y == 0)
{
Prime = false;
break;
}
}
}
return Prime;
}
Click Here to View the Output:
Insert the initial and final interval of the prime numbers: 23 87 Prime numbers between 23 and 87 are: 29 31 37 41 43 47 53 59 61 67 71 73 79 83
Click Here to View the Explanation:
- A
type variable is declaredboolean
.check
- The function
is created. It is markedTestPrimeNumber ()
if the number is not a prime number andfalse
true
otherwise. - The code for checking the prime number is inserted in the new function.
- The function is then called in the
function. If it is true,main ()
is displayed on the screen.It is a prime number
.