Dynamic Comparison Operators in PHP

Dynamic Comparison Operators in PHP

How about a small class:

class compare
{
  function is($op1,$op2,$c)
  {
     $meth = array('===' => 'type_equal', '<' => 'less_than');
     if($method = $meth[$c]) {
        return $this->$method($op1,$op2);
     }
     return null; // or throw excp.
  }
  function type_equal($op1,$op2)
  {
      return $op1 === $op2;
  }
  function less_than($op1,$op2)
  {
      return $op1 < $op2;
  }
}

Dynamically select a comparison operator (=, =, etc) in a conditional?

function lt($a, $b)
{
  return $a < $b;
}

 ...

$relops = Array(
  '<' => 'lt',
   ...
);

echo $relops['<'](2, 3);

PHP Dynamic operator usage

You can write a function with a switch case inside. like that:

$operator = '<='; // this can be '<=' or '<' or '>=' etc.

// I need like this something
$value1 = 2;
$value2 = 3;

function dyn_compare ($var1, $operator, $var2) {
    switch ($operator) {
        case "=":  return $var1 == $var2;
        case "!=": return $var1 != $var2;
        case ">=": return $var1 >= $var2;
        case "<=": return $var1 <= $var2;
        case ">":  return $var1 >  $var2;
        case "<":  return $var1 <  $var2;
    default:       return true;
    }   
}

//Then you can use

if (dyn_compare($value1, $operator, $value2)) {
    echo 'yes';
}

Alternatively you can work with match like @Justinas suggested. But this only works with php 8 and upwards

How to use condition operator pulled from database and added to script with PHP

The only way you can do what you show is with eval(). But it's generally frowned upon to use eval() because it introduces lots of potential security vulnerabilities.

I would do this hard-coded, to avoid eval() and make sure I can control the specific operators I want to support:

$cond_operator = "<"; // (but this operator actually pulled from database)

switch ($cond_operator) {
  case "<":
    if ( $actual_value < $score_value ) {
      return $result;
    }
    break;
  case ">":
    if ( $actual_value > $score_value ) {
      return $result;
    }
    break;
  case "==":
    if ( $actual_value == $score_value ) {
      return $result;
    }
    break;
  default:
    trigger_error("Unsupported condition operator: '$cond_operator'");
}

Using a variable as an operator

No, that syntax isn't available. The best you could do would be an eval(), which would not be recommended, especially if the $e came from user input (ie, a form), or a switch statement with each operator as a case

switch($e)
{
    case "||":
        if($a>$b || $c>$d)
            echo 'yes';
    break;
}

Dynamic logical expression parsing/evaluation in PHP?

Check create_function, it creates an anonymous function from the string parameters passed, I'm not sure about its performance, but it's very flexible...

Can I use operator in variable

Look into the eval() function. Though, I would say you should look into closures and even arrow functions.

$operator = fn($x) => $x >= 90;
$val = 100;
if($operator($val)){
    echo "Correct!";
}

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