regex.h - regular expression matching types
#include <regex.h>
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
- [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_.
None.
None.
None.
<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
First released in Issue 4.
Originally derived from the ISO POSIX-2 standard.
The REG_ENOSYS constant is marked obsolescent.
The restrict keyword is added to the prototypes for regcomp(), regerror(), and regexec().
A statement is added that the size_t type is defined as described in <sys/types.h>.