The <regex.h> include file declares the type size_t and defines the following regular expression functions:
| regcomp | regerror |
| regexec | regfree |
<regex.h> also declares the regex_t type, which is capable of storing a compiled regular expression, and the following macros:
REG_EXTENDED:
REG_ICASE
REG_NEWLINE
REG_NOSUB Values of the cflags parameter of the
regcomp function
REG_NOTBOL:
REG_NOTEOL Values of the eflags parameter of the regexec function
REG_* Values of the errcode parameter of the regerror function