diff --git a/math/check_prime.cpp b/math/check_prime.cpp new file mode 100644 index 00000000000..e517d774e8f --- /dev/null +++ b/math/check_prime.cpp @@ -0,0 +1,58 @@ +/** + * Copyright 2020 @author omkarlanghe + * + * @file + * A simple program to check if the given number if prime or not. + * + * @brief + * Reduced all possibilities of a number which cannot be prime. + * Eg: No even number, except 2 can be a prime number, hence we will increment our loop with i+2 jumping on all odd numbers only. + * If number is <= 1 or if it is even except 2, break the loop and return false telling number is not prime. + */ +#include +#include + /** + * Function to check if the given number is prime or not. + * @param num number to be checked. + * @return if number is prime, it returns @ true, else it returns @ false. + */ +template +bool is_prime(T num) { + bool result = true; + if (num <= 1) { + return 0; + } else if (num == 2) { + return 1; + } else if ((num & 1) == 0) { + return 0; + } + if (num >= 3) { + for (T i = 3 ; (i*i) < (num) ; i = (i + 2)) { + if ((num % i) == 0) { + result = false; + break; + } + } + } + return (result); +} + +/** + * Main function + */ +int main() { + int num; + std::cout << "Enter the number to check if it is prime or not" << + std::endl; + std::cin >> num; + bool result = is_prime(num); + if (result) { + std::cout << num << " is a prime number" << + std::endl; + } else { + std::cout << num << " is not a prime number" << + std::endl; + } + assert(is_prime(50) == false); + assert(is_prime(115249) == true); +}