php：如何使用变量变量通过索引获取数组中的元素

Question

If I have:

<?php
$params=[
    [
        'string'
    ]
];
//params get from $this->params()->fromPost();
$abc='params[0][0]';//$abc dynamiccly

I cannot access $params[0]

How to get string element?

I try to use

echo $$abc;

But

Notice: Undefined variable params[0][]

Answer 1

If $abc is defined dynamically, you have to split it in two variables : $arrayName and $arrayKey, as such :

$params = array('string');
$abc = 'params[0]';
$arrayName = substr($abc,0,strpos($abc,'['));
$arrayIndex = preg_replace('/[^\d\s]/', '',$abc);
echo ${$arrayName}[$arrayIndex]; // returns "string"