 the yield of <b>pcre2_regcomp()</b> is non-zero, you must not attempt
to use the contents of the <i>preg</i> structure. If, for example, you pass it
to <b>pcre2_regexec()</b>, the result is undefined and your program is likely to
crash.
</p>
<h2><a name="SEC5" href="#TOC1">MATCHING NEWLINE CHARACTERS</a></h2>
<p>
This area is not simple, because POSIX and Perl take different views of things.
It is not possible to get PCRE2 to obey POSIX semantics, but then PCRE2 was
never intended to be a POSIX engine. The