Are Windows window classes case-sensitive?

Question

MS docs being clear as mud (and the class name strings not referenced very often), I was wondering whether the class name of a Win32 window class is actually case sensitive?

Activism

Strange, just trying it should have been quicker than typing the question. Which then might have produced an interesting question: what case comparison rules does it use? – Covered

@Hans: What purpose, exactly, does your comment serve? No, typing the question was actually ... hmmm ... I'd say factor 15 faster than trying it out. (And after trying it out, I'd still haven't known that it is because it's an ATOM and I'd still been left wondering whether I tested the right thing, because calling any of the Win32 functions involved isn't exactly what I'm doing day to day.) – Activism

Answer 1

They are not case-sensitive. Window class names are string ATOMS, and according to MSDN,

• Case is not significant in searches for an atom name in an atom table. Also, the entire string must match in a search operation; no substring matching is performed.
• The string associated with a string atom can be no more than 255 bytes in size. This limitation applies to all atom functions.

Walford