Prime number c++

bool isPrime(int x = 0)
{
    /* Without extra 'count' variable */
    //! corner case: 0 and 1 aren't prime numbers
    if (x == 0 || x == 1)
        return 0;

    for (int i = 2; i <= x / 2; i++)
    {
        if (x > 2 && x % i == 0)
            return 0;
    }

    return 1;
}

#include<iostream>
using namespace std;
 
int main()
{
	int n;
	bool c=1;
	cin >> n;
	if (n <= 1)
	{
		cout << "NO\n";
	}
	else
	{
		for (int i = 2; i < n; i++)
		{
			if (n % i == 0)
			{
				c=0;
				break;
			}
		}
		if (!c)
			cout << "NO\n";
		else
			cout << "YES\n";
	}
	return 0;
}

Source: codejudge.blogspot.com

# Prime number:

n = int(input("Please enter your input number: "))
if n>1:
    for i in range(2,n):
        if n%i == 0:
            print("%d is a Not Prime."%n)
            break
    else:
        print("%d is a Prime."%n)
else:
    print("%d is a Not Prime."%n)
    
# Use to Definition Function:

'''
def Prime_number_chcek(n):
    if n>1:
        for i in range(2,n):
            if n%i == 0:
                return ("%d is a Not Prime."%n)
        return ("%d is a Prime."%n)
    return ("%d is a Not Prime."%n)

# Main Driver:
if __name__=="__main__":
    n = int(input("Enter your input number: "))
    print(Prime_number_chcek(n))
'''

bool prime(int a) { 
    if (a < 2)
        return false;
    for (int i = 2; i * i <= a; i++) {
        if (a % i == 0)
            return false;
    }
    return true;
}

#include<iostream>
using namespace std;
bool isPrimrNumber(int number){
	bool isPrimeFlag=true;
	for(int i=2;i<number;i++){
	if(number%i==0){
		isPrimeFlag=false;
		break;
	}
}
		return isPrimeFlag;
}
int main()
{
	int number;
	cout<<"Please enter your number";
	cin>>number;
		bool isPrimeFlag=isPrimeNumber(number)
	if(isPrimeFlag)
	{
		cout<<"prime Number";
	}
	else
	{
		cout<<"not prime number";
	}
}

#include <math.h>
// time: O(sqrt(n)) ..  space: O(1)
bool isPrime(int n) {
  if (n < 2) return false;
  int iter = 2;
  while(iter <= sqrt(n)) {
  	if (n % iter == 0) return false;
    iter++;
  }
  return true;
}

bool prime(int x) {
	if (x == 2 || x == 3) return true;
	if (x == 1 || x % 2 == 0 || x % 3 == 0) return false;
	int k = -1;
	while (k<=int(sqrt(x))) {
      	k+=6;
		if (x % k == 0 || x % (k+2) == 0) break;
	}
	return k>int(sqrt(x));
}

template<class T> bool isPrime(T n) 
{ 
	T i;
  	if(i<2) return false;
	for(i = 2; i * i <= n; i++) { 
    	if(n % i == 0)  return false; 
    } 
	return true; 
}

#include<iostream>
#include<cmath>
using namespace std;
int main(){
    int n;
    cin>>n;
    for(int i=2;i<sqrt(n)+1;i++){
        if(n%i==0){
            cout<<"number is not a prime";
            return 0;
        }
    }
    cout<<"number is a prime";
    return 0;
}

// A optimized school method based C++ program to check
// if a number is prime
#include <bits/stdc++.h>
using namespace std;
  
bool isPrime(int n)
{
    // Corner cases
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;
  
    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return false;
  
    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;
  
    return true;
}
  
// Driver Program to test above function
int main()
{
    isPrime(11) ? cout << " true\n" : cout << " false\n";
    isPrime(15) ? cout << " true\n" : cout << " false\n";
    return 0;
}

Source: geeksforgeeks.org

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