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C ctype (ctype.h) Library


C ctype Functions

The <ctype.h> header provides many functions for classifying and modifying characters.

Function Description
isalnum() Checks whether a character is alphanumeric
isalpha() Checks whether a character is a letter
isblank() Checks whether a character is a space or tab
iscntrl() Checks whether a character is a control character
isdigit() Checks whether a character is a decimal digit
isgraph() Checks whether a character has a graphical representation
islower() Checks whether a character is a lowercase letter
isprint() Checks whether a character is a printable character
ispunct() Checks whether a character is a punctuation character
isspace() Checks whether a character is a whitespace character
isupper() Checks whether a character is an uppercase letter
isxdigit() Checks whether a character is a hexadecimal digit
tolower() Returns a lowercase version of a character
toupper() Returns an uppercase version of a character


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