PHP 变量的四大作用域

<?php
$x = 50; // 全局变量
function myTest()
{
    $y = 100; // 局部变量
}

<?php
$x = 50;
$y = 100;
function myTest()
{
    global $x, $y;
    $y = $x + $y;
}
myTest();
echo $y;  // 输出 150

<?php
$x = 50;
$y = 100;
function myTest()
{
    $GLOBALS[&#39;y&#39;] = $GLOBALS[&#39;x&#39;] + $GLOBALS[&#39;y&#39;];
} 
myTest();
echo $y;

<?php
function myTest()
{
    static $x = 0;
    echo $x;
    $x++;
    echo PHP_EOL;
}
myTest();
myTest();
myTest();

<?php
function myTest($x)
{
    echo $x;
}
myTest(&#39;Galois&#39;);
myTest(8888);

echo &#39;<pre class="brush:php;toolbar:false">&#39;;
print_r($arr);