php: How to get element in array by index using variable-variables

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][]

Your $params is not an array. Use array syntax to use $params[0] property — Sunil Pachlangia
– Sunil Pachlangia, Commented Aug 23, 2016 at 10:04
I was edited question just now. But $abc is dynamically. So I cannot use this way. Anyway, thank @SunilPachlangia. — Hào Nghiêm Xuân
– Hào Nghiêm Xuân, Commented Aug 23, 2016 at 10:13
Basically you can't do that directly as you're trying. You have two options. First is to parse $abc string to get separately variable name and index value (e.g. as roberto06 showed in his answer), but that's not efficient to do so much work only to get variable's value. I would suggest (if possible) to change your data flow design which is in this case the incoming value from POST. — Jakub Matczak
– Jakub Matczak, Commented Aug 23, 2016 at 10:16

roberto06 · Accepted Answer · 2016-08-23 10:12:48Z

2

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"

answered Aug 23, 2016 at 10:12

roberto06

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1 Comment

Afshan Shujat Over a year ago

You have defined the variable dynamically, you can access the value using loop -

AmmyTech · Accepted Answer · 2016-08-23 10:08:17Z

2

use below way to access string

$params=[
    'string'
];
$abc='params';

$new = $$abc;
echo $new[0];

answered Aug 23, 2016 at 10:08

AmmyTech

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Comments

Afshan Shujat · Accepted Answer · 2016-08-23 10:25:11Z

0

For accessing the values of dynamic varible you can execute a loop-

<?php
$params=[
    'string'
];
$abc= 'params';

foreach($$abc as $k=>$v){
    echo $v;
}

?>

If you want to access it directly by index so you need to reassign the dynamic variable in another variable like $newArr = $$abc and then access $newArr.

answered Aug 23, 2016 at 10:25

Afshan Shujat

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