regex.h(7POSIX) POSIX Programmer's Manual regex.h(7POSIX)
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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 reg‐
comp(), 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 parame‐
ter 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 parame‐
ter 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.
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 discrep‐
ancy 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)