Assigning a if statement's condition to a variable

Question

Is it possible to assign a conditional statement into a variable and use it in an if statement? For example, I have the following code where the condition in the if statement will change from time to time:

<?php       
   $x = 2;
   
   //This "x > 5" value will come from a database
   $command = "x > 5";//Some times this value might be x > 5 || x == 1
  
   if($command)//This will always be true no matter what since the content of the $command is not empty
        echo "x is bigger than 5";
   else
        echo "x is smaller than 5";//I want this line to get executed since x is smaller than 5 in this case
?>

Expected output is x is smaller than 5, but what I get is x is bigger than 5

I wrote this answer to a similar question: https://stackoverflow.com/a/50280727/2734189. maybe you could use something like that. — Don't Panic, Jul 01 '21 at 21:14

score 1 · Accepted Answer · answered Jul 01 '21 at 21:04

1

You need to use eval(). $command will have to contain $ before the variables so it's valid PHP syntax.

$x = 2;
$command = '$x > 5';
$result = eval("return ($command);");
if ($result) {
    echo "x is bigger than 5";
} else {
    echo "x is smaller than 5";
}

Since eval() can execute arbitrary code, you should be extremely careful about what you allow to be put into $command.

answered Jul 01 '21 at 21:04

Barmar

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Thank you so much for explaining this with an sample code. Apricate your help. – D P. Jul 01 '21 at 21:12
1

@DP. although it may be worth reading https://stackoverflow.com/questions/951373/when-is-eval-evil-in-php – Nigel Ren Jul 01 '21 at 21:17

Assigning a if statement's condition to a variable

1 Answers1