CType
Ctype refers to a set of character handling facilities provided by the C standard library, exposed through the header ctype.h. The functions in this module classify characters or convert their case. They are widely used for parsing, input validation, and text processing.
The typical functions include isalpha, isdigit, isalnum, isspace, iscntrl, isgraph, isprint, ispunct, isupper, islower, and isxdigit,
The tests are locale-sensitive to the current C locale, which can be changed with setlocale (locale.h). This
Implementation details vary by compiler, but most implementations use a lookup table of character properties. The
Other notes: They do not perform encoding conversions; they work on the byte values of the input