CODEWITHSUNDEEP
phpif-statementconditional-statements
Jasper Jye
Jasper Jye

Reputation: 81

string to if else statment

I must use those strings to do the condition. Because of the $op is string, so it cannot run the condition correctly. Please help.

<?php 
  //$op = $condition[$i]. " " .$operant[$i]. " " .$participant_index;
    $op = "1 == 5";
    if($type[$i]=="person" && $op){
      echo "ok";
    }
 ?>

Upvotes: 0

Views: 246

Answers (4)

Ashique C M
Ashique C M

Reputation: 683

Try this code:

<?php
    //$op = $condition[$i]. " " .$operant[$i]. " " .$participant_index;
    $op = "1 == 5";
    if($type[$i]=="person" && eval("return $op;"))
    {
       echo "ok";
    }
?>

Upvotes: 0

ojovirtual
ojovirtual

Reputation: 3362

If you can guarantee that the value of $op isn't evil, then use eval:

if ($type[$i]=="person" && eval("return ".$op){
    echo "ok";
}

Be carefull with this, as it will parse the content of $op as PHP code.

Upvotes: 1

deceze
deceze

Reputation: 522081

You need to evaluate that string as code, PHP won't do that implicitly for you.
eval() can do that, but since eval will freely execute any and all code you give it using full PHP permissions, this is a giant security risk, depending on where those strings come from.

The better solution is to use a limited expression engine which parses and evaluates the string, being able to only handle a few select expressions. You could write something like this yourself, but the difficulty of that greatly depends on what expressions you may possibly allow. The Symfony framework offers a decent ExpressionLanguage component which can already do just that.

Upvotes: 2

Kris
Kris

Reputation: 41837

The easy (but potentially harmful) way:

$op = "1 == 5";

if (eval("return " . $op . ";")) {
    // do your thing.
}

see http://php.net/eval

Upvotes: 0

Related Questions