function.create-function.html

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    </b></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">process</span><span style="color: #007700">(</span><span style="color: #0000BB">$var1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$var2</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$farr</span><span style="color: #007700">)<br />{<br />&nbsp;&nbsp;&nbsp;&nbsp;foreach&nbsp;(</span><span style="color: #0000BB">$farr&nbsp;</span><span style="color: #007700">as&nbsp;</span><span style="color: #0000BB">$f</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #0000BB">$f</span><span style="color: #007700">(</span><span style="color: #0000BB">$var1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$var2</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></span><span style="color: #FF8000">//&nbsp;create&nbsp;a&nbsp;bunch&nbsp;of&nbsp;math&nbsp;functions<br /></span><span style="color: #0000BB">$f1&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'if&nbsp;($a&nbsp;&gt;=0)&nbsp;{return&nbsp;"b*a^2&nbsp;=&nbsp;".$b*sqrt($a);}&nbsp;else&nbsp;{return&nbsp;false;}'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$f2&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"return&nbsp;\"min(b^2+a,&nbsp;a^2,b)&nbsp;=&nbsp;\".min(\$a*\$a+\$b,\$b*\$b+\$a);"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$f3&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'if&nbsp;($a&nbsp;&gt;&nbsp;0&nbsp;&amp;&amp;&nbsp;$b&nbsp;!=&nbsp;0)&nbsp;{return&nbsp;"ln(a)/b&nbsp;=&nbsp;".log($a)/$b;&nbsp;}&nbsp;else&nbsp;{&nbsp;return&nbsp;false;&nbsp;}'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$farr&nbsp;</span><span style="color: #007700">=&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$x,$y'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'return&nbsp;"some&nbsp;trig:&nbsp;".(sin($x)&nbsp;+&nbsp;$x*cos($y));'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$x,$y'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'return&nbsp;"a&nbsp;hypotenuse:&nbsp;".sqrt($x*$x&nbsp;+&nbsp;$y*$y);'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$a,$b'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$f1</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$a,$b'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$f2</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$a,$b'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$f3</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;);<br /><br />echo&nbsp;</span><span style="color: #DD0000">"\nUsing&nbsp;the&nbsp;first&nbsp;array&nbsp;of&nbsp;anonymous&nbsp;functions\n"</span><span style="color: #007700">;<br />echo&nbsp;</span><span style="color: #DD0000">"parameters:&nbsp;2.3445,&nbsp;M_PI\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">process</span><span style="color: #007700">(</span><span style="color: #0000BB">2.3445</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">M_PI</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$farr</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;now&nbsp;make&nbsp;a&nbsp;bunch&nbsp;of&nbsp;string&nbsp;processing&nbsp;functions<br /></span><span style="color: #0000BB">$garr&nbsp;</span><span style="color: #007700">=&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$b,$a'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'if&nbsp;(strncmp($a,&nbsp;$b,&nbsp;3)&nbsp;==&nbsp;0)&nbsp;return&nbsp;"**&nbsp;\"$a\"&nbsp;'</span><span style="color: #007700">.<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'and&nbsp;\"$b\"\n**&nbsp;Look&nbsp;the&nbsp;same&nbsp;to&nbsp;me!&nbsp;(looking&nbsp;at&nbsp;the&nbsp;first&nbsp;3&nbsp;chars)";'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$a,$b'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">';&nbsp;return&nbsp;"CRCs:&nbsp;"&nbsp;.&nbsp;crc32($a)&nbsp;.&nbsp;"&nbsp;,&nbsp;".crc32(b);'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$a,$b'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">';&nbsp;return&nbsp;"similar(a,b)&nbsp;=&nbsp;"&nbsp;.&nbsp;similar_text($a,&nbsp;$b,&nbsp;&amp;$p)&nbsp;.&nbsp;"($p%)";'</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;);<br />echo&nbsp;</span><span style="color: #DD0000">"\nUsing&nbsp;the&nbsp;second&nbsp;array&nbsp;of&nbsp;anonymous&nbsp;functions\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">process</span><span style="color: #007700">(</span><span style="color: #DD0000">"Twas&nbsp;brilling&nbsp;and&nbsp;the&nbsp;slithy&nbsp;toves"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"Twas&nbsp;the&nbsp;night"</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$garr</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>The above example will output:</p></div>
    <div class="example-contents"><pre>
<div class="cdata"><pre>
Using the first array of anonymous functions
parameters: 2.3445, M_PI
some trig: -1.6291725057799
a hypotenuse: 3.9199852871011
b*a^2 = 4.8103313314525
min(b^2+a, a^2,b) = 8.6382729035898
ln(a/b) = 0.27122299212594

Using the second array of anonymous functions
** &quot;Twas the night&quot; and &quot;Twas brilling and the slithy toves&quot;
** Look the same to me! (looking at the first 3 chars)
CRCs: -725381282 , 1908338681
similar(a,b) = 11(45.833333333333%)
</pre></div>
    </pre></div>
   </div>
  </p>
  <p class="para">
   But perhaps the most common use for of lambda-style (anonymous) functions
   is to create callback functions, for example when using
   <a href="function.array-walk.html" class="function">array_walk()</a> or <a href="function.usort.html" class="function">usort()</a>
  </p>
  <p class="para">
   <div class="example">
    <p><b>Example #3 Using anonymous functions as callback functions</b></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$av&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">"the&nbsp;"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"a&nbsp;"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"that&nbsp;"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"this&nbsp;"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">array_walk</span><span style="color: #007700">(</span><span style="color: #0000BB">$av</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'&amp;$v,$k'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'$v&nbsp;=&nbsp;$v&nbsp;.&nbsp;"mango";'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$av</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>The above example will output:</p></div>
    <div class="example-contents"><pre>
<div class="cdata"><pre>
Array
(
  [0] =&gt; the mango
  [1] =&gt; a mango
  [2] =&gt; that mango
  [3] =&gt; this mango
)
</pre></div>
    </pre></div>
    <div class="example-contents"><p>
     an array of strings ordered from shorter to longer
    </p></div>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$sv&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">"small"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"larger"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"a&nbsp;big&nbsp;string"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"it&nbsp;is&nbsp;a&nbsp;string&nbsp;thing"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$sv</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>The above example will output:</p></div>
    <div class="example-contents"><pre>
<div class="cdata"><pre>
Array
(
  [0] =&gt; small
  [1] =&gt; larger
  [2] =&gt; a big string
  [3] =&gt; it is a string thing
)
</pre></div>
    </pre></div>
    <div class="example-contents"><p>
     sort it from longer to shorter
    </p></div>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$sv</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">create_function</span><span style="color: #007700">(</span><span style="color: #DD0000">'$a,$b'</span><span style="color: #007700">,</span><span style="color: #DD0000">'return&nbsp;strlen($b)&nbsp;-&nbsp;strlen($a);'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$sv</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>The above example will output:</p></div>
    <div class="example-contents"><pre>
<div class="cdata"><pre>
Array
(
  [0] =&gt; it is a string thing
  [1] =&gt; a big string
  [2] =&gt; larger
  [3] =&gt; small
)
</pre></div>
    </pre></div>
   </div>
  </p>
 </div>


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