Sample code demonstration of PHP static variable static_PHP tutorial

This function is of little use in because it will set the value of $w3sky to 0 and output "0" every time it is called. Increasing the variable $w3sky++ by one has no effect, because the variable $w3sky does not exist once this function is exited. To write a counting function that will not lose this count value, define the variable $w3sky as static:

Example using PHP static variable static

<ol class="dp-xml">
<li class="alt"><span><span class="tag"><span> ?PHP  </span></span></span></li>
<li><span>function Test(){  </span></li>
<li class="alt">
<span>static $</span><span class="attribute">w3sky</span><span> = </span><span class="attribute-value">0</span><span>;  </span>
</li>
<li><span>echo $w3sky;  </span></li>
<li class="alt"><span>$w3sky++;  </span></li>
<li><span>}  </span></li>
<li class="alt">
<span class="tag">?&gt;</span><span> </span>
</li>
</ol>

Now, every Each time the Test() function is called, the value of $w3sky will be output and incremented by one.

Static variables also provide a way to deal with recursive functions. A recursive function is a function that calls itself. Be careful when writing recursive functions, as they may recurse indefinitely. You must ensure that there are adequate ways to terminate recursion. Consider this simple function that recursively counts to 10, using the static variable $count to determine when to stop:

Example PHP static variable static and recursive function

<ol class="dp-xml">
<li class="alt"><span><span class="tag"><span> ?PHP  </span></span></span></li>
<li><span>function Test(){  </span></li>
<li class="alt">
<span>static $</span><span class="attribute">count</span><span> = </span><span class="attribute-value">0</span><span>;  </span>
</li>
<li><span>$count++;  </span></li>
<li class="alt"><span>echo $count;  </span></li>
<li>
<span>if ($count </span><span class="tag"><span> </span><span class="tag-name">10</span><span>) {  </span></span>
</li>
<li class="alt"><span>Test();  </span></li>
<li><span>}  </span></li>
<li class="alt"><span>$count--;  </span></li>
<li><span>}  </span></li>
<li class="alt">
<span class="tag">?&gt;</span><span> </span>
</li>
</ol>

Note: Static variables can be declared as shown in the above example. Assigning it with the result of an expression in a declaration will result in a parsing error.

Example Declare PHP static variable static

<ol class="dp-xml">
<li class="alt"><span><span class="tag"><span> ?PHP  </span></span></span></li>
<li><span>function foo(){  </span></li>
<li class="alt">
<span>static $</span><span class="attribute">int</span><span> = </span><span class="attribute-value">0</span><span>;// correct  </span>
</li>
<li>
<span>static $</span><span class="attribute">int</span><span> = </span><span class="attribute-value">1</span><span>+2; // wrong (as it is an expression_r_r)  </span>
</li>
<li class="alt">
<span>static $</span><span class="attribute">int</span><span> = </span><span class="attribute-value">sqrt</span><span>(121); // wrong (as it is an expression_r_r too)  </span>
</li>
<li><span>$int++;  </span></li>
<li class="alt"><span>echo $int;  </span></li>
<li><span>}  </span></li>
<li class="alt">
<span class="tag">?&gt;</span><span> </span>
</li>
</ol>

http://www.bkjia.com/PHPjc/446285.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/446285.htmlTechArticleThis function is of little use because every time it is called, the value of $w3sky will be set to 0 and "0" will be output. ". $w3sky++ that increases the variable by one has no effect, because once this function exits, the variable...