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 structure type regex_t shall contain at least the following member:

              size_t    re_nsub    Number of parenthesized subexpressions.

       The type size_t shall be defined as described in <sys/types.h> .

       The type regoff_t shall be defined as a signed integer type  that  can  hold  the  largest
       value  that  can  be  stored  in  either  a type off_t or type ssize_t. The structure type
       regmatch_t shall contain 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.

       Values for the cflags parameter to the regcomp() function are as follows:

       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>.

       Values for the eflags parameter to the regexec() function are as follows:

       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 following constants shall be defined 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 '\' 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.

       REG_ENOSYS
              Reserved.

       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 IEEE Std 1003.1-2001, regcomp(), the Shell
       and Utilities volume of IEEE Std 1003.1-2001

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  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 .