PHP website development variable scope_PHP tutorial

1. There is no global static variable in PHP.

When I used to do .Net development, I could use the following method to cache some data:

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public class Test {
private static int Count = 0; //This variable is valid throughout the application.
}

public class Test{
private static int Count = 0; //This variable is valid throughout the application.
}

PHP 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. Understand variable scope.

Variables declared outside the method cannot be accessed within the method body.
For example:

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$url = "www.webjx.com";
function _DisplayUrl() {
echo $url;
}
function DisplayUrl() {
global $url;
echo $url;
}
_DisplayUrl();
DisplayUrl();
?>

$url = "www.webjx.com";
function _DisplayUrl() {
echo $url;
}
function DisplayUrl(){
global $url;
echo $url;
}
_DisplayUrl();
DisplayUrl();
?>

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:

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function _DisplayUrl() {
global $myName;
$myName=yibin;
}

_DisplayUrl( );
echo $myName; //output yibin
?>

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