My First C ++ Program (Determining Prime Factors of a Number)

[august30]

#include <iostream>
#include <string>

using namespace std;
bool chk(int i);
string prime = " is already a prime number";
string factor = " is a prime factor";

int main()
{
	loop3:
		cout << "Enter Number:\n";
		int i;
		cin >> i;

		if (chk(i) == true)
		{
			cout << i << prime << endl;
		}
		else
		{
			int x = 2;
			int r = 0;
		loop:
			if (i%x == 0)
			{
				cout << x << factor << endl;
				i = i / x;
				r = r + x;
				goto loop;

			}
			else
			{
				int z = 3;
			loop2:
				if (z != i)
				{
					if (i%z == 0)
					{
						cout << z << factor << endl;
						i = i / z;
						r = r + z;
						goto loop2;
					}
					else
					{
						z = z + 1;
						goto loop2;
					}
				}
				else
				{
					cout << z << factor << endl;
					r = r + z;
					cout << r << " is the Sum of all Prime Factors" << endl;
					if (chk(r) == true)
					{
						cout << "The Sum is a Prime" << endl;
					}
					else
					{
						cout << "The Sum is NOT a Prime" << endl;
					}

				}

			}

		}
	
	loop4:
	cout << "try again? Y or N?"  << endl;
	string input;
	cin >> input;
	if (input == "Y")
	{
		goto loop3;
	}
	else
	{
		if (input == "N")
		{
			return 0;
		}
		else
		{
			cout << "What? Please Enter Correctly" << endl;
			goto loop4;
		}
	}

	system("pause");
}

bool chk(int i)
{
	for (int x = 2; x < i; x++)
	{
		if (i%x == 0)
		{
			return false;
		}
	}
	return true;
}

Do you have any suggestion about this?
I am new in C++,
and I am Happy with the output.
is there anything unnecessary in my code?
Please tell me.

[jlb]

is there anything unnecessary in my code?
Please tell me.

The goto statement is unnecessary, learn to use the other more accepted loop statements like do{}, do{}while(); and for( ; ; ) along with functions and meaningful variable names.

[mobotus]

Yes drop the goto(s) and look into control structures for c.

http://www.cplusplus.com/doc/tutorial/control/

Also I am not a real big fan of multiple returns in a function like that. You could rethink the logic in the chk().

// Program to print all prime factors
#include <iostream>
#include <cmath>

// A function to print all prime factors of a given number n
void primeFactors(int n)
{

	// Print the number of 2s that divide n
	while (n % 2 == 0)
	{
		std::cout << "2 ";
		n = n / 2;
	}

	// n must be odd at this point.  So we can skip one element (Note i = i +2)
	for (int i = 3; i <= sqrt(n); i = i + 2)
	{
		// While i divides n, print i and divide n
		while (n%i == 0)
		{
			std::cout << i << ' ';
			n = n / i;
		}
	}

	// This condition is to handle the case when n is a prime number
	// greater than 2
	if (n > 2)
		std::cout << n << ' ';
}

/* Driver program to test above function */
int main()
{
	int n = 1000;
	primeFactors(n);
	return 0;
}

Adapted from: http://www.geeksforgeeks.org/print-all-prime-factors-of-a-given-number/

[august30]

Wow! Thank you very much for your replies.
I will try it again.