The PCRE extension is a core PHP extension, so it is always enabled.
By default, this extension is compiled using the bundled PCRE
library. Alternatively, an external PCRE library can be used by
passing in the --with-pcre-regex=DIR
configuration option where DIR is the location of
PCRE's include and library files. It is recommended to use PCRE 8.10 or newer;
as of PHP 7.3.0, PCRE2 is required.
PCRE's just-in-time compilation is supported by default, which can be disabled with the --without-pcre-jit configuration option as of PHP 7.0.12.
The Windows version of PHP has built-in support for this extension. You do not need to load any additional extensions in order to use these functions.
PCRE is an active project and as it changes so does the PHP functionality that relies upon it. It is possible that certain parts of the PHP documentation is outdated, in that it may not cover the newest features that PCRE provides. For a list of changes, see the » PCRE library changelog and also the following bundled PCRE history:
| PHP Version | Updated PCRE Version | Notes |
|---|---|---|
| 8.2.0 | 10.40 | |
| 8.1.0 | 10.39 | |
| 7.4.12, 8.0.0 | 10.35 | |
| 7.4.6 | 10.34 | |
| 7.4.0 | 10.33 | |
| 7.3.0 | 10.32 | |
| 7.2.0 | 8.41 | |
| 7.0.3 | 8.38 | See CVE-2015-8383, CVE-2015-8386, CVE-2015-8387, CVE-2015-8389, CVE-2015-8390, CVE-2015-8391, CVE-2015-8393, CVE-2015-8394 |
| 7.0.0 | 8.37 | See CVE-2015-2325, CVE-2015-2326 |
From PHP version 7.3, 'pcre2' is used instead of 'pcre'. It is bundled with the PHP source, or a preinstalled pcre2 can be used if it was compiled with these configure-options:
--enable-shared --enable-unicode --enable-jit
If you want to use preinstalled pcre2 with PHP, use configure-options --with-pcre-dir=<path> and --with-pcre-regex=<path> (I don't know why there is two of them).