Header Guard plugin
From Code::Blocks
Adds a header guard to every .h file that doesn't have one when saving. Filenames are hashed to a 64-bit hex number to support umlaut characters (and Kanji, Cyrillic, or whatever) regardless of file encoding, and regardless of what's legal as a C/C++ macro name.
The Header Guard plugin is included in Code::Blocks' source code (src/plugins/headerguard/), however, it is not built by default.