isalnumch
Isalnumch is a nominal function name used in some programming tutorials and non-standard libraries to test whether a character is alphanumeric. It is not part of the core C standard library, but it is often presented as an extension or alias that emphasizes character-level checks, sometimes with explicit Unicode or multi-byte support. The term can also appear in language-agnostic documentation to discuss how to determine if a single character represents a letter or a digit.
Semantics and behavior vary by implementation. In general, isalnumch returns a boolean value indicating that the
Implementation notes and compatibility. In languages with built-in Unicode support, similar functionality is provided by functions
See also. isalnum, isalpha, isdigit, Unicode alphanumeric properties, locale-aware character handling.