iswalpha

 

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Technical Specifications

Symbol index

 

Strings library

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Null-terminated wide strings

Functions
Character manipulation
iswalnum (C95) iswalpha (C95) iswlower (C95) iswupper (C95) iswdigit (C95) iswxdigit (C95) iswblank (C99) wctype (C95) iswctype (C95)	iswcntrl (C95) iswgraph (C95) iswspace (C95) iswprint (C95) iswpunct (C95) towlower (C95) towupper (C95) wctrans (C95) towctrans (C95)
Conversions to numeric formats
wcstolwcstoll (C95)(C99) wcstoulwcstoull (C95)(C99)	wcstofwcstodwcstold (C99)(C95)(C99) wcstoimaxwcstoumax (C99)(C99)
String manipulation
wcslenwcsnlen_s (C95)(C11) wcscpywcscpy_s (C95)(C11) wcsncpywcsncpy_s (C95)(C11) wcscatwcscat_s (C95)(C11) wcsncatwcsncat_s (C95)(C11) wcsstr (C95)	wcscmp (C95) wcsncmp (C95) wcscoll (C95) wcsxfrm (C95) wcschr (C95) wcsrchr (C95) wcspbrk (C95) wcsspn (C95) wcscspn (C95) wcstokwcstok_s (C95)(C11)
Array manipulation
wmemcpywmemcpy_s (C95)(C11) wmemmovewmemmove_s (C95)(C11)	wmemcmp (C95) wmemchr (C95) wmemset (C95)

 

Defined in header <wctype.h>
int iswalpha( wint_t ch );		(since C95)

Checks if the given wide character is an alphabetic character, i.e. either an uppercase letter (ABCDEFGHIJKLMNOPQRSTUVWXYZ), a lowercase letter (abcdefghijklmnopqrstuvwxyz) or any alphabetic character specific to the current locale.

Parameters

ch

-

wide character

Return value

Non-zero value if the wide character is an alphabetic character, zero otherwise.

Notes

ISO 30112 specifies which Unicode characters are include in POSIX alpha category.

Example

Run this code

#include <locale.h>
#include <stdio.h>
#include <wchar.h>
#include <wctype.h>
 
int main(void)
{
    wchar_t c = L'\u0b83'; // Tamil sign Visarga ('ஃ')
    printf("in the default locale, iswalpha(%#x) = %d\n", c, !!iswalpha(c));
    setlocale(LC_ALL, "en_US.utf8");
    printf("in Unicode locale, iswalpha(%#x) = %d\n", c, !!iswalpha(c));
}

Possible output:

in the default locale, iswalpha(0xb83) = 0
in Unicode locale, iswalpha(0xb83) = 1

References

• C23 standard (ISO/IEC 9899:2024):

• TBD The iswalpha function (p: TBD)

• C17 standard (ISO/IEC 9899:2018):

• 7.30.2.1.2 The iswalpha function (p: 327)

• C11 standard (ISO/IEC 9899:2011):

• 7.30.2.1.2 The iswalpha function (p: 448-449)

• C99 standard (ISO/IEC 9899:1999):

• 7.25.2.1.2 The iswalpha function (p: 394-395)

See also

isalpha	checks if a character is alphabetic (function)
C++ documentation for iswalpha

ASCII values			characters	iscntrl iswcntrl	isprint iswprint	isspace iswspace	isblank iswblank	isgraph iswgraph	ispunct iswpunct	isalnum iswalnum	isalpha iswalpha	isupper iswupper	islower iswlower	isdigit iswdigit	isxdigit iswxdigit
decimal	hexadecimal	octal
0–8	\x0–\x8	\0–\10	control codes (NUL, etc.)	≠0	0	0	0	0	0	0	0	0	0	0	0
9	\x9	\11	tab (\t)	≠0	0	≠0	≠0	0	0	0	0	0	0	0	0
10–13	\xA–\xD	\12–\15	whitespaces (\n, \v, \f, \r)	≠0	0	≠0	0	0	0	0	0	0	0	0	0
14–31	\xE–\x1F	\16–\37	control codes	≠0	0	0	0	0	0	0	0	0	0	0	0
32	\x20	\40	space	0	≠0	≠0	≠0	0	0	0	0	0	0	0	0
33–47	\x21–\x2F	\41–\57	!"#$%&'()*+,-./	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
48–57	\x30–\x39	\60–\71	0123456789	0	≠0	0	0	≠0	0	≠0	0	0	0	≠0	≠0
58–64	\x3A–\x40	\72–\100	:;<=>?@	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
65–70	\x41–\x46	\101–\106	ABCDEF	0	≠0	0	0	≠0	0	≠0	≠0	≠0	0	0	≠0
71–90	\x47–\x5A	\107–\132	GHIJKLMNOP QRSTUVWXYZ	0	≠0	0	0	≠0	0	≠0	≠0	≠0	0	0	0
91–96	\x5B–\x60	\133–\140	[\]^_`	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
97–102	\x61–\x66	\141–\146	abcdef	0	≠0	0	0	≠0	0	≠0	≠0	0	≠0	0	≠0
103–122	\x67–\x7A	\147–\172	ghijklmnop qrstuvwxyz	0	≠0	0	0	≠0	0	≠0	≠0	0	≠0	0	0
123–126	\x7B–\x7E	\173–\176	{|}~	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
127	\x7F	\177	backspace character (DEL)	≠0	0	0	0	0	0	0	0	0	0	0	0