java - Trying to count blank spaces in a string recursively?

Question

EDIT: Really sorry, I mean Java! As for what I think, I would say the first contains if statement is for s == null or length 0, but I'm confused as to what to put in the

return spaceCount(s.substring(1, ......)) + ......;

part.

I'm trying to use some if statements to write a function that takes a string as a parameter and recursively coutns the number of blanks spaces " " it has. So far I have

public static int spaceCount (string s) {
    if ( ...... ) {
        return 0;
    }
    char c = s.charAt(0);
    if (....... ) {
        return spaceCount (.....);
    } else {
        return spaceCount(s.substring(1, ......)) + ......;
    }
}

So in the first if statement, should I write the case of the string having zero length? I'm pretty sure that won't cover the case of no spaces at all, so I'm not sure how to proceed.

For the second and third, I know I have to scan the string for spaces, but I am not really sure how to do that either. Any hints or direction would be appreciated!

Answer 1

public static int spaceCount(final String s) {

    if(s == null || s.length() == 0) {
        return 0;
    }

    char c = s.charAt(0);
    if(' ' != c) {
        return spaceCount(s.substring(1));
    } else {
        return spaceCount(s.substring(1)) + 1;
    }

}

You don't have to "scan the string for spaces", that's what the recursion passing the remainder of the string does.