FreeBSD Manual Pages
regex_compile(3) rationL User Manual regex_compile(3) NAME regex_compile regex_free - Compile a regular expression from a pattern SYNOPSIS #include <rationl.h> reg_t regex_compile(char* pattern); void regex_free(reg_t re); DESCRIPTION regex_compile() takes a regular expression pattern and compiles it into a regular expression matching the pattern. The value returned is a reg_t structure containing the folowing fields: typedef struct reg_t { Automaton* aut; char* pattern; } regex_t; aut This fields hold a compiled automaton that matches the pattern passed as argument to the compile function. This automaton will then be used by the other function to performs the operations on the automa- ton. pattern This fields hold the pattern passed as argument. REGULAR EXPRESSION FORMAT Currently supported regular expression operators are : ? Corresponds to zero or one occurence of the element. For instance, the regular expression aa? will match a and aa but will not match aaa. * Corresponds to zero, one or several the the precedent element. The regular expression a* matches an empty string, a, aaaa... but will not match ab. + Corresponds to at least one element. The regular expression a+ will match a, aa, aaaaaa... but will not match an empty string. {n} Repeats the element n times. For instance the regular expression b{4} wil match only match bbbb. {n,} Repeats at least the element n times. The regular expression b{4,} wil match bbbb, bbbbb... but will not match bb or bbb. {n,p} Repeats between n and p times the element preceding the . The regular expression b{4,} wil match bbbb, bbbbb... but will not match bb or bbb. a|b Matches expression a or b. For instance the regular expression a|b will match a and b but will not match ab. This operator as the lowest precedence meaning that aa|bb will match either aa or bb. () When a pattern or an expression is put between parenthesis, it en- forces precedence. For example the regular expression defined as (aa)? will match if aa occurs zero or one time. [] This operator creates a group of caracters than can be matched. Consider the regular expression [abc]. This expression will match a, b or c. When a group is defined using - like in [A-Z] it will match all the caracters in the ASCII order contained between A and Z. To match all alphanumerical word you can use the folowing expression [A-Za-z0-9] that will match either a caracter between A and Z, a caracter between a and z or a number between 0 and 9. \w This is equivalent to writing [A-Za-z0-9_]. Matches all alphanumer- ical words including and underscores. \W This matches everything except all the caracters in \w \d This is equivalent to writing [0-9]. Matches all numbers. \D This matches everything except all the caracters in \d \s Matches all blank characters (\t, \n, \r, \v) and spaces. \S Matches everything that is not a blank character. RETURN VALUE regex_compiles() returns a element of the reg_t struct or NULL on fail- ure to compile the regular expression. This regular expression needs to be freed using the regex_free() func- tion. rationL 0.1.0 April 5, 2021 regex_compile(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=regex_free&sektion=3&manpath=FreeBSD+Ports+15.0>