Variable scope in PHP website development_PHP tutorial

1. There is no global static variable in PHP

When I was doing .NET development, I could use the following method to cache some data:

view plaincopy to clipboardprint?<p></p><p>　public class Test { <br>private static int Count = 0; //该变量在整个应用程序中都有效。 <br>} <br>public class Test{ <br>private static int Count = 0; //该变量在整个应用程序中都有效。 <br>} </p>

PGP is an interpreted language. Although it has the static modifier, its meaning is completely different from that in .NET.

Even if a variable in the class is declared as static, this variable is only valid in the current page-level application domain.

2. Understanding variable scope

Variables declared outside the method cannot be accessed within the method body.

For example:

view plaincopy to clipboardprint?<p></p><p><?php   <br>$url = "www.51cto.com"; <br>function _DisplayUrl() { <br>echo $url; <br>} <br>function DisplayUrl() { <br>global $url; <br>echo $url; <br>} <br>_DisplayUrl(); <br>DisplayUrl(); <br>?> <br><br>$url = "www.51cto.com"; <br>function _DisplayUrl() { <br>echo $url; <br>} <br>function DisplayUrl(){ <br>global $url; <br>echo $url; <br>} <br>_DisplayUrl(); <br>DisplayUrl(); <br>?> </p>

The

_DisplayUrl method will not display any results because the variable $url is inaccessible in the method body _DisplayUrl. Just add global before $url, such as the DisplayUrl method.

Global variables defined in the method body can be accessed outside the method:

view plaincopy to clipboardprint?<p></p><p>　 <?php   <br>function _DisplayUrl() { <br>global $myName; <br>$myName='yibin'; <br>} <br>_DisplayUrl(); <br>echo $myName; //output yibin <br>?></p>

What you are reading is "Variable Scope in PHP Website Development"

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