If conditions inside a php variable

Question

i already looked in the existing questions but nothing was close to my situation.

I would like to express a condition inside a variable. The problem is that if I use:

if($condition) {

it is true if $condition has a value, while i would like to make it true if the content of the variable is true:

$condition = “$a < 3”;
if($condition) {

The idea is that I store the conditions in the database, and I use them inside a while() according to the situation. I don’t know if I was clear, sorry if I wasn’t.

Hope you got the question, and thanks in advance!

jeprubio · Accepted Answer · 2020-03-08T04:02:56.803

2

It seems you are looking for php eval https://www.php.net/manual/en/function.eval.php

$test = 'return $a < 3;';
$test2 = 'return $a < 1;';

$a = 2;

if (eval($test)) {
    echo 'a < 3 ';
} else {
    echo 'a > 3 ';
}


if (eval($test2)) {
    echo 'a < 1 ';
} else {
    echo 'a > 1 ';
}

prints a < 3 a > 1

Be careful because $test = "return $a < 3;"; would not compile as the var $a is not defined at that point so you should use single quotes so that its content is not interpreted.

edited Mar 08 '20 at 04:02

answered Mar 08 '20 at 03:52

jeprubio

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`eval` can be dangerous. You might look at the [Symfony Expression Language](https://symfony.com/doc/current/components/expression_language/introduction.html) as an alternative. – Greg Schmidt Mar 08 '20 at 04:54
1

@jeprubio thank you so much! eval() is the function i was looking for :) – Translations Cloud Mar 08 '20 at 16:22

Rudra · Answer 2 · 2020-03-08T12:36:18.543

0

$condition = ‘$_POST[‘abc’] == “xyz”’; In this line you are using single inverted comma which will make it string $condition = $_POST[‘abc’] == “xyz"; This will return boolean.

edited Mar 08 '20 at 12:36

answered Mar 08 '20 at 03:41

Rudra

704
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@TranslationsCloud oh, Sorry I think this link may help https://stackoverflow.com/questions/52315387/evaluate-string-as-condition-php – Rudra Mar 08 '20 at 12:40

If conditions inside a php variable

2 Answers2