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 <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 parameter to the regcomp() function:
- REG_EXTENDED
- Use Extended Regular Expressions.
- REG_ICASE
- Perform pattern matching in a case-insensitive manner.
- REG_MINIMAL
- Change default matching behavior to leftmost shortest possible match. Only applicable to REG_EXTENDED regular expressions.
- 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 parameter 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_.
None.
None.
None.
XSH regcomp
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> .
SD5-XBD-ERN-60 is applied.
The obsolescent REG_ENOSYS constant is removed.
This reference page is clarified with respect to macros and symbolic constants.
Austin Group Defect 793 is applied, adding REG_MINIMAL.
Austin Group Defect 1031 is applied, changing the description of REG_ICASE.
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