函数里面如何由参数变量$what得到$what_1?

Question

函数里面如何由参数变量$what得到$what_1?<?php
$good_1="good";
$bad_1="bad";function hello($what){
echo $what_1; // 请问这里怎么写才让输入$what变量输出$what_1变量内容？
}hello("good");?>

Answer 1

<?php
$good_1="good";
$bad_1="bad";function hello($what){
    $new = $what.'_1';
    echo $GLOBALS[$new];
}hello("good");?>

Answer 2

$good_1="good";
$bad_1="bad";function hello($what){
    global $good_1,$bad_1;
    eval("echo $".$what."_1;");
}hello("good");

Answer 3

function hello($what){
    $v =  "{$what}_1";
    echo $$v;
}