PHP流程控制方法

<?php

#if
if (T_ABSTRACT==356){}elseif (T_ABSTRACT==222){}elseif (T_ABSTRACT==322){}else{}

#switch
$a = null;
switch ($a){
    case 1:
        echo "a的值是1";
        break;
    case 2:
        echo "a的值是2";
        break;
    case 3:
        echo "a的值是3";
        break;
    case 4:
        echo "a的值是4";
        break;
    default:
        echo '这个a的值很神秘';
        break;
}

#while
while (true){
    echo '<br>';
    echo '你好，php菜鸟';
    break;
}

#for
$aa = 100;
for($i = 0; $i <= $aa; $i++){
    echo $i."我是第 $i 个数据";
    echo '<br>';
}
exit(0);
echo "sadasdasdasdas";