#include <regex.h>
The <regex.h> header defines the structures and symbolic constants used by the regcomp(), regexec(), regerror(), and regfree() functions. See regcomp(3C).
The structure type regex_t contains the following member:
size_t re_nsub number of parenthesized subexpressions
The type size_t is defined as described in <sys/types.h>. See types.h(3HEAD).
The type regoff_t is 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 contains 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:
use extended regular expressions
ignore case in match
report only success or fail in regexec()
change the handling of NEWLINE character
Values for the eflags parameter to the regexec() function are as follows:
The circumflex character (^), when taken as a special character, does not match the beginning of string.
The dollar sign ($), when taken as a special character, does not match the end of string.
The following constants are defined as error return values:
regexec() failed to match.
Invalid regular expression.
Invalid collating element referenced.
Invalid character class type referenced.
Trailing '\' in pattern.
Number in \digit invalid or in error.
“[]” imbalance.
“\(\)” or “()” imbalance.
“\{\}” imbalance.
Content of “\{\}” invalid: not a number, number too large, more than two numbers, first larger than second.
Invalid endpoint in range expression.
Out of memory.
'?', '*', or '+' not preceded by valid regular expression.
Reserved.
See attributes(5) for descriptions of the following attributes:
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