isblank(), isblank_l()

space or tab character test 



#include <ctype.h>

int isblank(int c);

int isblank_l(int c, locale_t locale);


The isblank() and isblank_l() function tests for a space or tab character. For any locale, this includes the following standard characters:

'\t' ' '

In the "C" locale, a successful isblank() test is limited to these characters only. The value of the argument must be representable as an unsigned char or the value of EOF.

The isblank_l() function takes an explicit locale argument, whereas the isblank() function uses the current global or per-thread locale.

In the C locale, isblank() returns true only for the standard white-space characters.

The behavior of the isblank() function is affected by the current locale. To modify the behavior, change the LC_CTYPE category in setlocale(), that is, setlocale(LC_CTYPE, newlocale). In the C locale or in a locale where character type information is not defined, characters are classified according to the rules of the U.S. ASCII 7-bit coded character set.

isblank_l() behaves in the same way as isblank() without the _l suffix, but uses the specified locale rather than the global or per-thread locale. A locale_t is returned by newlocale().



Is an integer whose value is representable as an unsigned char, or the value of the macro EOF.


Is a locale_t perhaps returned by newlocale() or LC_GLOBAL_LOCALE or 0 for the current thread locale set with uselocale().


The isblank() and isblank_l() functions return non-zero for true and zero for false. If the parameter is not in the domain of the function or locale is invalid, the return result is undefined.


isblank() conforms to ANSI/ISO 9899:1999 'ISO C99'. isblank_l() conforms to IEEE Std 1003.1-2008 'POSIX.1'.


MT-Safe, with exceptions.

The function isblank() is MT-Safe as long as no thread calls setlocale() while this function is executing.

The function isblank_l() is MT-Safe as long as no thread calls freelocale() on locale while this function is executing.




PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Professional Developers 64-Bit Edition
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition


isalnum(), isalnum_l(), isalpha(), isalpha_l(), isascii(), isascii_l(), iscntrl(), iscntrl_l(), isdigit(), isdigit_l(), isgraph(), isgraph_l(), islower(), islower_l(), isprint(), isprint_l(), ispunct(), ispunct_l(), isspace(), isspace_l(), isupper(), isupper_l(), isxdigit(), isxdigit_l(), newlocale(), setlocale()

PTC MKS Toolkit 10.4 Documentation Build 39.