check_prime.cpp File Reference

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+6 jumping and check for i or i+2 to be a factor of the number; if it's a factor then we will return false otherwise true after the loop terminates at the terminating condition which is (i*i<=num) More...

#include <cassert>
#include <iostream>

Include dependency graph for check_prime.cpp:

Functions
template<typename T >
bool	is_prime (T num)
	for IO operations More...
int	main ()

Detailed Description

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+6 jumping and check for i or i+2 to be a factor of the number; if it's a factor then we will return false otherwise true after the loop terminates at the terminating condition which is (i*i<=num)

Copyright 2020

Author

omkarlanghe

A simple program to check if the given number if prime or not.

Function Documentation

is_prime()

template<typename T >

bool is_prime

(

T

num

)

for IO operations

for assert Function to check if the given number is prime or not.

Parameters

num	number to be checked.

Returns

if number is prime, it returns @ true, else it returns @ false.

                     {
    bool result = true;
    if (num <= 1) {
        return false;
    } else if (num == 2 || num == 3) {
        return true;
    } else if ((num % 2) == 0 || num % 3 == 0) {
        return false;
    } else {
        for (T i = 5; (i * i) <= (num); i = (i + 6)) {
            if ((num % i) == 0 || (num % (i + 2) == 0)) {
                result = false;
                break;
            }
        }
    }
    return (result);
}

main()

int main

(

void

)

Main function

           {
    // perform self-test
    assert(is_prime(50) == false);
    assert(is_prime(115249) == true);
 
    int num = 0;
    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;
    }
 
    return 0;
}

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