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<title>Finds the length of the initial segment of a string consisting
entirely of characters contained within a given mask</title>
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<div class="refnamediv">
<h1 class="refname">strspn</h1>
<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">strspn</span> — <span class="dc-title">
Finds the length of the initial segment of a string consisting
entirely of characters contained within a given mask
</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.strspn-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">int</span> <span class="methodname"><strong>strspn</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$subject</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$mask</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$start</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$length</code></span>
]] )</div>
<p class="para rdfs-comment">
Finds the length of the initial segment of <code class="parameter">subject</code>
that contains <em class="emphasis">only</em> characters from <code class="parameter">mask</code>.
</p>
<p class="para">
If <code class="parameter">start</code> and <code class="parameter">length</code>
are omitted, then all of <code class="parameter">subject</code> will be
examined. If they are included, then the effect will be the same as
calling <em>strspn(substr($subject, $start, $length),
$mask)</em> (see <a href="function.substr.html" class="xref">substr</a>
for more information).
</p>
<p class="para">
The line of code:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$var </span><span style="color: #007700">= </span><span style="color: #0000BB">strspn</span><span style="color: #007700">(</span><span style="color: #DD0000">"42 is the answer to the 128th question."</span><span style="color: #007700">, </span><span style="color: #DD0000">"1234567890"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
will assign <em>2</em> to <var class="varname"><var class="varname">$var</var></var>,
because the string "42" is the initial segment
of <code class="parameter">subject</code> that consists only of characters
contained within "1234567890".
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.strspn-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<code class="parameter">subject</code></dt>
<dd>
<p class="para">
The string to examine.
</p>
</dd>
<dt>
<code class="parameter">mask</code></dt>
<dd>
<p class="para">
The list of allowable characters.
</p>
</dd>
<dt>
<code class="parameter">start</code></dt>
<dd>
<p class="para">
The position in <code class="parameter">subject</code> to
start searching.
</p>
<p class="para">
If <code class="parameter">start</code> is given and is non-negative,
then <span class="function"><strong>strspn()</strong></span> will begin
examining <code class="parameter">subject</code> at
the <code class="parameter">start</code>'th position. For instance, in
the string '<em>abcdef</em>', the character at
position <em>0</em> is '<em>a</em>', the
character at position <em>2</em> is
'<em>c</em>', and so forth.
</p>
<p class="para">
If <code class="parameter">start</code> is given and is negative,
then <span class="function"><strong>strspn()</strong></span> will begin
examining <code class="parameter">subject</code> at
the <code class="parameter">start</code>'th position from the end
of <code class="parameter">subject</code>.
</p>
</dd>
<dt>
<code class="parameter">length</code></dt>
<dd>
<p class="para">
The length of the segment from <code class="parameter">subject</code>
to examine.
</p>
<p class="para">
If <code class="parameter">length</code> is given and is non-negative,
then <code class="parameter">subject</code> will be examined
for <code class="parameter">length</code> characters after the starting
position.
</p>
<p class="para">
If <code class="parameter">length</code> is given and is negative,
then <code class="parameter">subject</code> will be examined from the
starting position up to <code class="parameter">length</code>
characters from the end of <code class="parameter">subject</code>.
</p>
</dd>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.strspn-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns the length of the initial segment of <code class="parameter">subject</code>
which consists entirely of characters in <code class="parameter">mask</code>.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
When a <code class="parameter">start</code> parameter is set, the returned length
is counted starting from this position, not from the beginning of
<code class="parameter">subject</code>.
</p>
</p></blockquote>
</div>
<div class="refsect1 examples" id="refsect1-function.strspn-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-6112">
<p><strong>Example #1 <span class="function"><strong>strspn()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// subject does not start with any characters from mask<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">strspn</span><span style="color: #007700">(</span><span style="color: #DD0000">"foo"</span><span style="color: #007700">, </span><span style="color: #DD0000">"o"</span><span style="color: #007700">));<br /><br /></span><span style="color: #FF8000">// examine two characters from subject starting at offset 1<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">strspn</span><span style="color: #007700">(</span><span style="color: #DD0000">"foo"</span><span style="color: #007700">, </span><span style="color: #DD0000">"o"</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">));<br /><br /></span><span style="color: #FF8000">// examine one character from subject starting at offset 1<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">strspn</span><span style="color: #007700">(</span><span style="color: #DD0000">"foo"</span><span style="color: #007700">, </span><span style="color: #DD0000">"o"</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
int(0)
int(2)
int(1)
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.strspn-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">This function is
binary-safe.</span></p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.strspn-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"><span class="function"><a href="function.strcspn.html" class="function" rel="rdfs-seeAlso">strcspn()</a> - Find length of initial segment not matching mask</span></li>
</ul>
</p>
</div>
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