php: Scope

js and php scopes difference

js in scope:

Global scope: anywhere (outside and function within a function) can be used

The local scope: function can only be used internally

PHP also has two scopes: global scope and local scope

Global scope: it can only be used outside the function

The local scope: it can only be used within the function

such as:

var a = 'zy'
function test () {
  console.log(a)
}
test()
// a 变量可以被访问到

Internal not external

<?php
$a = 'zy'
function test () {
  var_dump($a)
}
test()
?>
// 报错：( ! ) Parse error: syntax error, unexpected 'function' (T_FUNCTION) in

External can not access the internal

<?php
function test () {
  $a = 'zy'
}
var_dump($a)
?>
// 报错：( ! ) Parse error: syntax error, unexpected '}' in

Use global keywords

<?php
function test ()
{
    global $a;
}
$a = 'zy';
var_dump($a);
test();
// 好使

Use $ GLOBALS

<?php
function test ()
{
    $GLOBALS['a'] = 'zy';
}
test();
var_dump($GLOBALS['a']);