Question

I have a operator in a string .

 $c['operator'] = ">=";

        if($sub_total.$c['operator'].$c['value'])
        {
        echo $sub_total.$c['operator'].$c['value'];

        }

it obtain output is 20610>=30000

Answer 1

I’d put the possible operators in a switch:

$result = null;

switch($c['operator'])
{

    case '>=':
        $result = $sub_total >= $c['value'];
    break;
    case '<=':
        $result = $sub_total <= $c['value'];
    break;

    // etc etc

}

This is far safer than using eval, and has the extra benefit that it sanitises the input.