Using conditional values from an array in an if...statement

Question

I have an array of conditions :

$arrConditions = array ('>=2', '==1', '<=10');

...which I want to be able to use in an if...statement.

IE.

if (5 $arrConditions[0])
{
  ...do something
}

...which would be the same as :

if (5 >= 2)
{
  ...do something
}

Any help?

Thanks

You can use eval, but it will be horribly slow and you didn't hear it from me. Or, much preferably, you can roll up your sleeves and do it manually: switch($operator) { case '==': $result = $input == $operand; } etc. — Jon
– Jon, Commented Feb 25, 2013 at 12:41
Yeah, I've done it manually but was just wondering if there was a more elegant solution... — ojsglobal
– ojsglobal, Commented Feb 25, 2013 at 12:44
Get some refresher on basics of programming. IF requires a condition which outputs true or false. $arrCondition[0] is just a string and there is no operation happening there. which means no evaluation and no output. you can use switch case for symbols but it is impossible in case of IF. — Abhinav Kulshreshtha
– Abhinav Kulshreshtha, Commented Feb 25, 2013 at 12:45
@Abhinav...no need to be rude! That's the whole question, as in, is it possible - which, by the way, it would be using eval(). — ojsglobal
– ojsglobal, Commented Feb 25, 2013 at 12:48

Your Common Sense · Accepted Answer · 2013-02-25 12:49:25Z

2

Such a requirement is a sure sign of a bad design.
Most likely you can do that another, more usual way.

Nevertheless, never use eval for such things.
At least store each operator in pairs - an operator and operand.

$arrConditions = array (
    array('>=',2),
    array('==',1),
    array('<=',10),
);

and then use switch:

list ($operator,$operand) = $arrConditions[0];
switch($operator) { 
    case '==': 
        $result = ($input == $operand); 
        break;
    case '>=': 
        $result = ($input >= $operand); 
        break;
    // and so on
}

But again - most likely you can solve it another, much easier way.

answered Feb 25, 2013 at 12:49

Your Common Sense

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Comments

Dino Babu · Accepted Answer · 2013-02-25 13:45:27Z

0

What about this ?

<?php

$arrConditions = array('==2', '==9', '==5', '==1', '==10', '==6', '==7');

$count = 0;
$myval = 0;
foreach ($arrConditions as $cond) {
  $str = "if(5 $cond) { return  $count;}";
  $evalval = eval($str);
  if (!empty($evalval)) {
    $myval = $count;
  }
  $count++;
}

switch ($myval) {
  case 0: echo '==2 satisfied';
    break;
  case 1: echo '==9 satisfied';
    break;
  case 2: echo '==5 satisfied';
    break;
  case 3: echo '==1 satisfied';
    break;
  case 4: echo '==10 satisfied';
    break;
  default : echo 'No condition satisfied';
}
?>

edited Feb 25, 2013 at 13:45

answered Feb 25, 2013 at 13:19

Dino Babu

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