C character classification

C standard library (libc)
General topics
Data types Character classification Strings Mathematics File input/output Date/time Localization Memory allocation Process control Signals Alternative tokens
Miscellaneous headers
<assert.h> <errno.h> <setjmp.h> <stdarg.h>

C character classification is a group of operations in the C standard library that test a character for membership in a particular class of characters; such as alphabetic, control, etc. Both single-byte, and wide characters are supported.