C Character Classification - Overview of Functions

Overview of Functions

The functions that operate on single-byte characters are defined in ctype.h header (cctype header in C++). The functions that operate on wide characters are defined in wctype.h header (cwctype header in C++).

The classification is done according to the current locale.

Byte character	Wide character	Description
`isalnum`	`iswalnum`	checks if a byte/`wchar_t` is alphanumeric
`isalpha`	`iswalpha`	checks if a byte/`wchar_t` is alphabetic
`islower`	`iswlower`	checks if a byte/`wchar_t` is lowercase
`isupper`	`iswupper`	checks if a byte/`wchar_t` is an uppercase byte/`wchar_t`
`isdigit`	`iswdigit`	checks if a byte/`wchar_t` is a digit
`isxdigit`	`iswxdigit`	checks if a byte/`wchar_t` is a hexadecimal byte/`wchar_t`
`iscntrl`	`iswcntrl`	checks if a byte/`wchar_t` is a control byte/`wchar_t`
`isgraph`	`iswgraph`	checks if a byte/`wchar_t` is a graphical byte/`wchar_t`
`isspace`	`iswspace`	checks if a byte/`wchar_t` is a space byte/`wchar_t`
`isblank`	`iswblank`	checks if a byte/`wchar_t` is a blank byte/`wchar_t` (C99/C++11)
`isprint`	`iswprint`	checks if a byte/`wchar_t` is a printing byte/`wchar_t`
`ispunct`	`iswpunct`	checks if a byte/`wchar_t` is a punctuation byte/`wchar_t`
`tolower`	`towlower`	converts a byte/`wchar_t` to lowercase
`toupper`	`towupper`	converts a byte/`wchar_t` to uppercase
	`iswctype`	checks if a `wchar_t` falls into specific class
	`towctrans`	converts a `wchar_t` using a specific mapping
	`wctype`	returns a wide character class to be used with `iswctype`
	`wctrans`	returns a transformation mapping to be used with `towctrans`

Read more about this topic: C Character Classification

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