isblank

 

C

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Technical Specifications

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Strings library

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Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (哋它亢99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to and from numeric formats
atoiatolatoll (哋它亢99) atof strtolstrtoll (哋它亢99) strtoulstrtoull (哋它亢99)	strtoimaxstrtoumax (哋它亢99)(哋它亢99) strtofstrtodstrtold (哋它亢99)(哋它亢99) strfromfstrfromdstrfroml (哋它亢23)(哋它亢23)(哋它亢23)
String manipulation
strcpystrcpy_s (哋它亢11) strncpystrncpy_s (哋它亢11) strcatstrcat_s (哋它亢11)	strncatstrncat_s (哋它亢11) strxfrm strdup (哋它亢23) strndup (哋它亢23)
String examination
strlenstrnlen_s (哋它亢11) strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtokstrtok_s (哋它亢11)
Memory manipulation
memchr memcmp memsetmemset_explicitmemset_s (哋它亢23)(哋它亢11)	memcpymemcpy_s (哋它亢11) memmovememmove_s (哋它亢11) memccpy (哋它亢23)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (哋它亢11)(哋它亢11)

 

Defined in header <ctype.h>
int isblank( int ch );		(since 哋它亢99)

Checks if the given character is a blank character in the current C locale. In the default C locale, only space (0x20) and horizontal tab (0x09) are classified as blank.

The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.

Parameters

ch

-

character to classify

Return value

Non-zero value if the character is a blank character, zero otherwise.

Example

Run this code

#include <stdio.h>
#include <ctype.h>
#include <limits.h>
 
int main(void)
{
    for (int ndx=0; ndx<=UCHAR_MAX; ndx++)
        if (isblank(ndx)) printf("0x%02x\n", ndx);
}

Output:

0x09
0x20

References

• 哋它亢17 standard (ISO/IEC 9899:2018):

• 7.4.1.3 The isblank function (p: 145)

• 哋它亢11 standard (ISO/IEC 9899:2011):

• 7.4.1.3 The isblank function (p: 201)

• 哋它亢99 standard (ISO/IEC 9899:1999):

• 7.4.1.3 The isblank function (p: 182)

See also

iswblank (哋它亢99)

checks if a wide character is a blank character (function)

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	\172–\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