Standard library header <cctype>

This header was originally in the C standard library as <ctype.h>.

This header is part of the null-terminated byte strings library.

Functions
isalnum	checks if a character is alphanumeric (function)
isalpha	checks if a character is alphabetic (function)
islower	checks if a character is lowercase (function)
isupper	checks if a character is an uppercase character (function)
isdigit	checks if a character is a digit (function)
isxdigit	checks if a character is a hexadecimal character (function)
iscntrl	checks if a character is a control character (function)
isgraph	checks if a character is a graphical character (function)
isspace	checks if a character is a space character (function)
isblank (C++11)	checks if a character is a blank character (function)
isprint	checks if a character is a printing character (function)
ispunct	checks if a character is a punctuation character (function)
tolower	converts a character to lowercase (function)
toupper	converts a character to uppercase (function)