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<h2 class="title">Delimiters</h2>
<p class="para">
When using the PCRE functions, it is required that the pattern is enclosed
by <em class="emphasis">delimiters</em>. A delimiter can be any non-alphanumeric,
non-backslash, non-whitespace character.
</p>
<p class="para">
Often used delimiters are forward slashes (<em>/</em>), hash
signs (<em>#</em>) and tildes (<em>~</em>). The
following are all examples of valid delimited patterns.
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
/foo bar/
#^[^0-9]$#
+php+
%[a-zA-Z0-9_-]%
</pre></div>
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</p>
<p class="para">
If the delimiter needs to be matched inside the pattern it must be
escaped using a backslash. If the delimiter appears often inside the
pattern, it is a good idea to choose another delimiter in order to increase
readability.
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
/http:\/\//
#http://#
</pre></div>
</div>
</div>
The <span class="function"><a href="function.preg-quote.html" class="function">preg_quote()</a></span> function may be used to escape a string
for injection into a pattern and its optional second parameter may be used
to specify the delimiter to be escaped.
</p>
<p class="para">
In addition to the aforementioned delimiters, it is also possible to use
bracket style delimiters where the opening and closing brackets are the
starting and ending delimiter, respectively.
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
{this is a pattern}
</pre></div>
</div>
</div>
</p>
<p class="para">
You may add <a href="reference.pcre.pattern.modifiers.html" class="link">pattern
modifiers</a> after the ending delimiter. The following is an example
of case-insensitive matching:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
#[a-z]#i
</pre></div>
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