PHP - Notice: Undefined variable [duplicate]

Question

I have a php file:

<?php
$a = 1;
function test(){ 
    echo $a;
} 
test();
?>

And I get this error:

Notice: Undefined variable: a in X:\...\test.php on line 4

Using XAMPP @ 32bit W7.

Answer 1

Variables have function scope. $a inside the function is not the same as $a outside the function. Inside the function you have not defined a variable $a, so it doesn't exist. Pass it into the function:

$a = 1;
function test($a) { 
    echo $a;
} 
test($a);