RegexBuddy User’s Guide
4 stars based on
It is the successor to the widely popular PCRE library. Both are open source regex set options binary written in C by Philip Hazel. The first PCRE2 release was given version number New features are added to PCRE2 only. The only real regex set options binary to do so would be to use the new search-and-replace feature. The regex syntax supported by PCRE2 Because of this, the regex tutorial on this website does not specifically mention PCRE2.
The only significant new feature is a new version check conditional. The syntax looks much like a conditional that checks a named backreferencebut the inclusion regex set options binary the equals sign and other symbols not allowed in capturing group names make it a syntax error in the original PCRE.
In all versions of PCRE2,? You can use any valid regex for the "yes" and "no" parts. If the regex set options binary check succeeds the "yes" part is regex set options binary. Otherwise the "no" part is attempted. This is exactly like a normal conditional that evaluates the part before or after the vertical bar depending on whether a capturing group participated in the match or not.
It matches no in PCRE2 Omitting the minor version number is the same as specifying. If you specify the minor version number you should use two digits after the decimal point.
Three or more digits are an error as of version Since the first release was You cannot omit the dot if you specify the minor version number. This version check conditional is mainly intended for people who use PCRE2 indirectly, via an application that provides regex support based on PCRE2 or a programming language that embeds PCRE2 but does not expose all its function calls. It allows them to find regex set options binary which version of PCRE2 the application uses.
UTF-8 characters consist of 1 to 4 bytes. UTF characters consist of 1 or 2 words. Do so before including the library, like this:. The functions without a suffix always use the code unit size you've defined.
The functions with suffixes remain available. So your application can use regular expressions with all three code unit sizes. But it is important not to mix them up. With PCRE2 you have to use various types regex set options binary context to pass certain compilation or matching options, such as line break handling. In PCRE these options could be passed directly as option bits when compiling or matching.
Before you can use a regular expression, it needs to be converted into a binary format for improved efficiency. Otherwise, pass the length in code units as the second parameter.
The 3rd parameter is a set of options combined with binary or. The 4th and 5th parameters receive error conditions. The final parameter is a context. Pass NULL unless you need special line break handling. The function returns a pointer to memory it allocated. You can reuse the same context for as many regex compilations as you like.
This does not work with PCRE2. But doing so has no effect. You have to use the match context. Pass the compiled regex as the first parameter, and NULL as the second.
The length and starting offset are in code regex set options binary, not characters. The function returns a positive number when the match succeeds. Any other non-positive return value indicates an error. Regex set options binary don't need to free this pointer.
The first two values in the array are the start and end of the overall match. The second pair is the match of the first capturing group, and so on. Pass the number or name of a capturing group, or zero for the overall match. PCRE2 does not provide a function that gives you all the matches of a regex in string. It never returns more than the first match.
This is not the same as incrementing the starting position before the call. The biggest item item that was forever on PCRE's wishlist was likely the ability to regex set options binary. The replacement string syntax is fairly simple. There is nothing Perl-compatible about it, though. The overall match is group number zero. To add literal dollar sign to the replacement, you need to double it up. Any single dollar sign that is not part of a valid backreference is an regex set options binary.
Like Python, but unlike Perl, PCRE2 treats backreferences to non-existent groups and backreferences to non-participating groups as errors. You can use the same compiled regex for both regex matching and regex substitution.
You don't need a match data object for substitution. The next parameters are for match data and match context which can both be set to NULL. Then pass the replacement string and the length of the replacement string. Finally pass a pointer to a buffer where the result string should be stored, along with a pointer to a variable that holds the size of the buffer. The buffer needs to have space for a terminating zero. All lengths and offsets are in code units, not characters. Zero means no matches were found.
A negative number indicates an error occurred. The variable that holds the size of the buffer is updated to indicate the length of the string that it written to the buffer, excluding the terminating zero. The terminating zero is written. Starting with version The biggest difference is that backslashes are no longer literals. A backslash followed by a character that is not a letter or digit escapes that character.
So you can escape dollar signs and backslashes with other backslashes to suppress their special meaning. If you want to have a literal backslash in your replacement, then you have to escape it with another backslash. Backslashes followed by a digit are an error.
Backslashes followed by a letter are an error, unless that combination forms a replacement string token. Case conversion is also supported. The syntax is the same as Perl, but the behavior is not.
With PCRE2, any case conversion escape cancels the preceding escape. Conditionals are supported using a newly invented syntax that extends the syntax for backreferences. You can use the full replacement string syntax in the two alternatives, including other conditionals. Case conversion runs through conditionals. Any case conversion in effect before the conditional also applies to the conditional.
If the conditional contains its own case conversion escapes in the part of the conditional that is actually used, regex set options binary those regex set options binary in effect after the conditional.
Did this website just save you a trip to the bookstore? Please make a donation to support this site, and you'll get a lifetime of advertisement-free access to this site! Credit cards, PayPal, and Bitcoin gladly accepted.