PHP global variable scope analysis_PHP tutorial

Copy code The code is as follows:

$a = 1;
include 'b.inc' ;
?>

This variable $a will take effect in the include file b.inc. However, in user-defined functions, a local function scope will be introduced. Any variables used inside a function will be restricted to the local function scope by default.

Copy code The code is as follows:

$a = 1; /* global scope */
function Test ()
{
echo $a ; /* reference to local scope variable */
}
Test ();
?>

This script will produce no output because the echo statement refers to a local version of the variable $a, and it is not assigned a value within this scope. You may notice that global variables in PHP are a little different from C language
Global variables in PHP must be declared as global (global keyword) when used in functions

Copy code The code is as follows:

$a = 1;
$b = 2;
function Sum ()
{
global $a , $b ;
$b = $a + $b ;
}
Sum ();
echo $b ;
?>

The output of the above script will be "3".

http://www.bkjia.com/PHPjc/320427.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/320427.htmlTechArticleCopy the code as follows: ?php $a = 1; include 'b.inc'; ? The variable $a here Will take effect in the include file b.inc. However, in a user-defined function, a local function scope will...