TD tutorial question

Looks like prudent programming. If the map is incorrectly initialized and there's a textureIndex = -1, you'll get an exception at tiletexture[textureIndex].

Also, slight correction: the intent is not to "break" the for-loop. It continues the for-loop (skipping the Draw call) with the next y-value.

EDIT: A more robust implementation would be

if( textureIndex < minTexIndex || textureIndex > maxTexIndex ) continue;

to ensure you attempt to access the tiletexture array with only valid indices.

Ahh i get it.

But if it skips one there would be a tile missing so an error anyway, does this make it more obvious that there is something wrong in the map array?

But if it skips one there would be a tile missing so an error anyway, does this make it more obvious that there is something wrong in the map array?

I have no idea if it would be obvious. As mentioned above, the intent is to prevent exceptions. A "skipped" tile would be the level designer's error.

Consider: you write a program to display tiles, leaving it up to a designer or the user to create data to input to your program. IMHO, the first duty of a programmer is to make life easy for the user. If a user runs your program and it crashes with a memory exception, who's the user going to blame - him/herself or you? More to the point, in fact, it's your fault because your code is not robust.

Admittedly, you can't make your code entirely fool-proof, because, when you do, the universe will create a better fool. However, a primary goal (if not THE primary goal) for coding any program is (or should be) to handle errors gracefully.

In this particular case, in addition to the index testing, a better approach would be to examine the data on input to ensure it's valid for use. Then, either inform the user that the data is incomplete and abort (not really friendly), or (more friendly) inform the user that the data is incomplete and some tiles just won't show, and ask the user if he/she wants to continue.