[Flint]

@tw: (a) and (b) are bool functions. while !(a) does not cause if !(a) to drop. while !(a) OR !(b) simply makes the decision to enter the loop or not.

Originally Posted by tw

Everytime (a) and (b) are executed - an new entry occurs.

Correct. That is what makes this work. The loop continuously evaluates, "falling through" true conditions and "catching" on false conditions. false conditions always prompt for a new password and immediately reevaluate the same condition. The loop continues to evaluate until it is able to "fall through" completely (exit the loop).

Here is the program running:

Please enter a password: a
Passwords must be at least 6 characters long
Please enter a password: abc
Passwords must be at least 6 characters long
Please enter a password: abcdef
Passwords must include at least on digit (1-9)
Please enter a password: 123
Passwords must be at least 6 characters long
Please enter a password: abcdef
Passwords must include at least on digit (1-9)
Please enter a password: a1
Passwords must be at least 6 characters long
Please enter a password: abc123
Thank you that is a valid password

Press Enter to close window...

Here is the code:

#include<iostream>
#include<cstring>
#include<cctype>
using namespace std;
	
	//Function checks the password for length.		(a)
	bool passLength(char[]);

	//Function checks the password for a digit.		(b)
	bool containDigit(char[]);
	
	const int SIZE = 21;
	char password[SIZE];

int main()
{
	cout << "Please enter a password: ";
	cin.getline(password, SIZE);
	
	while ((!passLength(password)) || (!containDigit(password)))  
		{
	if	(!passLength(password))
		(passLength(password));						//(a)

	if	(!containDigit(password))
		(containDigit(password));					//(b)	
		}

	cout << "Thank you that is a valid password" << endl;
	
	
	//Keep the window open until Enter key is pressed.
	cout << "\nPress Enter to close window..." << endl;
	std::cin.get();

	return 0;
}	

	bool passLength(char password[])				//(a)
{
	int lengthPass = 6;
	int length = strlen(password);
	
		if (lengthPass <= length)
			return true;
		else 
			{
			cout << "Passwords must be at least 6 characters long" << endl;
			cout << "Please enter a password: ";
			cin.getline(password, SIZE);
			return false;
			}
}


	bool containDigit(char password[])				//(b)
{
	int index = 0;
	int length = strlen(password);
	
	for (index = 0; index < length; index++ )
	{
		if (isdigit(password[index]))
			return true;
	}
		cout << "Passwords must include at least on digit (1-9)" << endl;
		cout << "Please enter a password: ";
		cin.getline(password, SIZE);		
		return false;
	
}