REGEX.H(7) Miscellaneous Information Manual REGEX.H(7)

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(3), regexec(3), regerror(3), and regfree(3) 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(3) 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(3) 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: [OB] 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.