regex.h(3)                 POSIX Programmer's Manual                regex.h(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       regex.h -- regular expression matching types

SYNOPSIS
       #include <regex.h>

DESCRIPTION
       The <regex.h> header shall define the structures and symbolic constants
       used by the regcomp(), regexec(), regerror(), and regfree() functions.

       The <regex.h> header shall define the regex_t structure type, which
       shall include at least the following member:


           size_t    re_nsub    Number of parenthesized subexpressions.

       The <regex.h> header shall define the size_t type as described in
       <sys/types.h>.

       The <regex.h> header shall define the regoff_t type as a signed integer
       type that can hold the largest value that can be stored in either a
       ptrdiff_t type or a ssize_t type.

       The <regex.h> header shall define the regmatch_t structure type, which
       shall include at least the following members:


           regoff_t    rm_so    Byte offset from start of string
                                to start of substring.
           regoff_t    rm_eo    Byte offset from start of string of the
                                first character after the end of substring.

       The <regex.h> header shall define the following symbolic constants for
       the cflags parameter to the regcomp() function:

       REG_EXTENDED  Use Extended Regular Expressions.

       REG_ICASE     Ignore case in match.

       REG_NOSUB     Report only success or fail in regexec().

       REG_NEWLINE   Change the handling of <newline>.

       The <regex.h> header shall define the following symbolic constants for
       the eflags parameter to the regexec() function:

       REG_NOTBOL    The <circumflex> character (''^^''), when taken as a special
                     character, does not match the beginning of string.

       REG_NOTEOL    The <dollar-sign> (''$$''), when taken as a special
                     character, does not match the end of string.

       The <regex.h> header shall define the following symbolic constants as
       error return values:

       REG_NOMATCH   regexec() failed to match.

       REG_BADPAT    Invalid regular expression.

       REG_ECOLLATE  Invalid collating element referenced.

       REG_ECTYPE    Invalid character class type referenced.

       REG_EESCAPE   Trailing <backslash> character in pattern.

       REG_ESUBREG   Number in \digit invalid or in error.

       REG_EBRACK    ""[[]]"" imbalance.

       REG_EPAREN    ""\\((\\))"" or ""(())"" imbalance.

       REG_EBRACE    ""\\{{\\}}"" imbalance.

       REG_BADBR     Content of ""\\{{\\}}"" invalid: not a number, number too
                     large, more than two numbers, first larger than second.

       REG_ERANGE    Invalid endpoint in range expression.

       REG_ESPACE    Out of memory.

       REG_BADRPT    ''??'', ''**'', or ''++'' not preceded by valid regular
                     expression.

       The following shall be declared as functions and may also be defined as
       macros. Function prototypes shall be provided.


           int    regcomp(regex_t *restrict, const char *restrict, int);
           size_t regerror(int, const regex_t *restrict, char *restrict, size_t);
           int    regexec(const regex_t *restrict, const char *restrict, size_t,
                      regmatch_t [restrict], int);
           void   regfree(regex_t *);

       The implementation may define additional macros or constants using
       names beginning with REG_.

       The following sections are informative.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <sys_types.h>

       The System Interfaces volume of POSIX.1-2017, regcomp()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                           regex.h(3)
