Global variable php global variable scope analysis

Copy the code The code is as follows:

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

Here the variable $a will be included in the file b.inc takes effect in. 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 not produce any output because the echo statement refers to a local version of the variable $a, and it is not assigned a value in this scope. You may notice that the global variables in PHP are a little different from the C language. Global variables in PHP must be declared as global (global keyword) when used in functions. Copy the code

The code is as follows:

< ?php $a = 1; $b = 2;

function Sum ()

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


The output of the above script will be "3".
The above introduces the global variable PHP global variable scope analysis, including the content of global variables. I hope it will be helpful to friends who are interested in PHP tutorials.