PROLOG

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

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.1‐2008, regcomp()

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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                                   2013                                       regex.h(7POSIX)