gjoel comments on My Last Resort - I Need Help Debugging my Program

[–] gjoel@programming.dev 3 points 5 months ago (5 children)

private char Advance() {
   	return source[current++];
   }

This is wrong. At least as I would expect advance to behave. While you do advance, you are returning the old value, not the new one. ++current would return the new value.

Also, it would help if you said what the wrong behaviour was.

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[+] dr_robotBones@reddthat.com [S] 1 point 5 months ago (4 children)

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[–] gjoel@programming.dev 2 points 5 months ago (1 child)

while (Peek() != '*' && PeekAhead() != '/' && !IsAtEnd()) {

Probably this guy.

If you encounter an asterisk or a slash, then it stops. You want to stop when you encounter an asterisk and a slash, so:

while (!(Peek() == '*' && PeekAhead() == '/') && !IsAtEnd()) {

I also find your detection of when to remove the comment a bit scary, but that might be because you haven't shown the Match method.

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[–] fruitcantfly@programming.dev 1 point 5 months ago (1 child)

It's not strictly speaking a bug, but the behavior of Advance is a bit confusing. Based on how you use it in the code snippets, I would suggest changing it to

private void Advance() {
    current++;
}

So that it only does what it says, and then changing the place where you read the next char to

char c = Peek();
Advance();

Alternatively, you could rename it to something like ReadChar, which more closely matches its current behavior, since a read is expected to return the data (character) at the current position, and then advance the position