Example: Check Prime Number
#include <iostream>
using namespace std;
bool checkPrimeNumber(int);
int main() {
int n;
cout << "Enter a positive integer: ";
cin >> n;
if (checkPrimeNumber(n))
cout << n << " is a prime number.";
else
cout << n << " is not a prime number.";
return 0;
}
bool checkPrimeNumber(int n) {
bool isPrime = true;
// 0 and 1 are not prime numbers
if (n == 0 || n == 1) {
isPrime = false;
}
else {
for (int i = 2; i <= n / 2; ++i) {
if (n % i == 0) {
isPrime = false;
break;
}
}
}
return isPrime;
}
Output
Enter a positive integer: 23 23 is a prime number.
In this example, the number entered by the user is passed to the checkPrimeNumber()
function.
This function returns true
if the number passed to the function is a prime number, and returns false
if the number passed is not a prime number.
The detailed logic of the checkPrimeNumber()
function is given in our C++ Prime Number tutorial.
Finally, the appropriate message is printed from the main()
function