isdigit function

[mw3284]

I'm creating a password verification program (using c-strings) with one of the criteria to have a number within it. My function is causing a fatal assertion error.

bool digit(char str[], const int LEN)
{	int count = 0;
	for(int i = 0; i < LEN; i++)
	{	if(isdigit(str[i]))
			count++;
	}
	if(count > 0)
		return true;
	else
	{	cout << "Password must have at least one number.\n";
		return false;
	}
}

Thanks ahead.

[hanst99]

Why is str not constant, and what do you call the function with?

[mw3284]

const int LENGTH = 21;
char input[LENGTH];
digit(input, LENGTH)

[hanst99]

Why do you pass an uninitialized array? Either way, you should pass LENGTH-1 -- you don't want to check the zero character at the end, do you?

Also... the error output really shouldn't be inside the digit function. You return a bool, so the client code can tell whether the check was successful, and decide how to handle that case.

Anyways, you are using VC++ right? Maybe you should just run the debugger and see what exact line causes the error.

[mw3284]

The array isn't uninitialized. Here is my code from main:

const int LENGTH = 21;
    char input[LENGTH];
	bool flag = false;
    cout << "Please enter a password: ";
    cin.getline(input, 20);
    do
	{	if(length(input) && capital(input) && digit(input, LENGTH) && symbol(input) && space(input))
			flag = true;
		else
		{	cout << "Please enter a password: ";
			cin.getline(input, 20);
		}
	}while(flag == false);
	
	cout << "You have entered a successful password. Thank you, goodbye.\n";

    return 0;

As you can see, if I put all my bool functions in an if statement, it doesn't leave room for error reporting unless I call the function again. I wanted to have criteria specific prompts for why the password isn't sufficient since I don't list them all out at the beginning.

I don't have any debugger code. The program compiles fine and then crashes.

[Lynx876]

Have you tried what Hanst99 said?

Why do you pass an uninitialized array? Either way, you should pass LENGTH-1 -- you don't want to check the zero character at the end, do you?

In case for any reason you're running off the end of the array for input.


Edit:
Ok, I just more or less copied your code and solved it. I think you were running off the end of the array.

int _tmain(int argc, _TCHAR* argv[])
{
	const int LENGTH = 21;

	char input[ LENGTH ];

	std::cout << "Enter text: ";
	std::cin.getline( input, LENGTH );

	int count = 0;

	int tempCount = strlen( input );

	for( int i = 0; i < tempCount; i++ )
	{
		if( isdigit( input[ i ] ) )
			count++;
	}

	std::cout << "There were " << count << " digits.\n\n";

	return 0;
}

The above code fixed my assertion failure. The use of strlen( input ) to get the actual size of the text entered rather than the size of the array and itterating through that ammount to check it all.

[hanst99]

I don't have any debugger code.

Yes you have, VC++ automatically generates it in the debug build.

[mw3284]

Yes, thank you linx. I was entering a password of six characters and my for loop was testing characters 1 to 21.

I replaced i < LEN with str[i]!='\0'