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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 .

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