cctype functions

I'm rather new at C/C++ and I'm having trouble understanding how these things work. I'm reading a tutorial on them but I don't understand the return values that I'm getting. Let's use the isdigit() function as an example, the tutorial says:

Quote:

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The isdigit() function returns non-zero for true and zero for false. If the parameter is not in the domain of the function, the return result is undefined.

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Now suppose that I use the following code:

Code:

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int var_one = 1;
 bool var_two = isdigit(var_one);
 cout << var_two << endl;

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The program will output a 0 for false, but var_one is a digit. What am I missing here?

isdigit(1);
Is false

isdigit('1');
is true

It's for testing characters which you might type in at the keyboard, or read from a text file.

Eg, if you ask the user to enter a number, and they enter "abc", you can use isdigit() to verify the data entry.

Thanks, I see where I was going wrong now -- expected the 1 to be evaluated as an an integer and not as a character :P