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### 3.10 `isspace`, `isspace_l`—whitespace character predicate

Synopsis

    #include <ctype.h>
    int isspace(int c);

    #include <ctype.h>
    int isspace_l(int c, locale_t locale);

Description
`isspace` is a macro which classifies singlebyte charset values by table lookup. It is a predicate returning non-zero for whitespace characters, and 0 for other characters. It is defined only when `isascii`(c) is true or c is EOF.

`isspace_l` is like `isspace` but performs the check based on the locale specified by the locale object locale. If locale is LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.

You can use a compiled subroutine instead of the macro definition by undefining the macro using ‘`#undef isspace`’ or ‘`#undef isspace_l`’.

Returns
`isspace`, `isspace_l` return non-zero if c is a space, tab, carriage return, new line, vertical tab, or formfeed (`0x09`–`0x0D`, `0x20`), or one of the other space characters in non-ASCII charsets.

Portability
`isspace` is ANSI C. `isspace_l` is POSIX-1.2008.

No supporting OS subroutines are required.