[Flint]

This is somewhat better, as far as a more streamlined main function...

#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;
}