January 1st, 2015

Horrifically nasty gotcha: FindResource and FindResourceEx

Raymond Chen
Raymond Chen

The Find­Resource­Ex function is an extension of the Find­Resource function in that it allows you to specify a particular language fork in which to search for the resource. Calilng the Find­Resource function is equivalent to calling Find­Resource­Ex and passing zero as the wLanguage.

Except for the horrible nasty gotcha: The second and third parameters to Find­Resource­Ex are in the opposite order compared to the second and third parameters to Find­Resource!

In other words, if you are adding custom language support to a program, you cannot just stick a wLanguage parameter on the end when you switch from Find­Resource to Find­Resource­Ex. You also have to flip the second and third parameters.

Original code Find­Resource(hModule, MAKEINTRESOURCE(IDB_MYBITMAP), RT_BITMAP)
You change it to Find­Resource­Ex(hModule, MAKEINTRESOURCE(IDB_MYBITMAP), RT_BITMAP, 0)
You should have changed it to Find­Resource­Ex(hModule, RT_BITMAP, MAKEINTRESOURCE(IDB_MYBITMAP), 0)

The nasty part of this is that since the second and third parameters are the same type, the compiler won’t notice that you got them backward. The only way you find out is that your resource code suddenly stopped working.

Category
Old New Thing
Topics
Code

Author

Raymond Chen

Raymond has been involved in the evolution of Windows for more than 30 years. In 2003, he began a Web site known as The Old New Thing which has grown in popularity far beyond his wildest imagination, a development which still gives him the heebie-jeebies. The Web site spawned a book, coincidentally also titled The Old New Thing (Addison Wesley 2007). He occasionally appears on the Windows Dev Docs Twitter account to tell stories which convey no useful information.

0 comments

Discussion are closed.