NAME

regex.h - regular-expression-matching types

SYNOPSIS

#include <regex.h>

DESCRIPTION

The <regex.h> header defines the structures and symbolic constants used by the regcomp(), regexec(), regerror() and regfree() functions.

The structure type regex_t contains at least the following member:

size_t    re_nsub    number of parenthesised subexpressions

The type regoff_t is defined as a signed arithmetic 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 contains 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:

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:

REG_NOTBOL

The circumflex character (^), when taken as a special character, will not match the beginning of string.

REG_NOTEOL

The dollar sign ($), when taken as a special character, will not match the end of string.

The following constants are 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

The implementation does not support the function.

The following are declared as functions and may also be declared as macros. Function prototypes must be provided for use with an ISO C compiler.

int    regcomp(regex_t *, const char *, int);
int    regexec(const regex_t *, const char *, size_t, regmatch_t[], int);
size_t regerror(int, const regex_t *, char *, size_t);
void   regfree(regex_t *);

The implementation may define additional macros or constants using names beginning with REG_.

APPLICATION USAGE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

regcomp(), the XCU specification.