regex.h
Section: POSIX Programmer's Manual (0P)
Updated: 2017
Page Index
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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 ('ha'),
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 .