Is there an easy way in PHP to convert from strings like '256M', '180K', '4G' to their integer equivalents?

Question

I need to test the value returned by ini_get(\'memory_limit\') and increase the memory limit if it is below a certain threshold, however this ini_get(\'me

Answer 1

I think you're out of luck. The PHP manual for ini_get() actually addresses this specific problem in a warning about how ini_get() returns the ini values.

They provide a function in one of the examples to do exactly this, so I'm guessing it's the way to go:

function return_bytes($val) {
    $val = trim($val);
    $last = strtolower($val[strlen($val)-1]);
    switch($last) {
        // The 'G' modifier is available since PHP 5.1.0
        case 'g':
            $val *= 1024;
        case 'm':
            $val *= 1024;
        case 'k':
            $val *= 1024;
    }

    return $val;
}

They have this to say about the above function: "The example above shows one way to convert shorthand notation into bytes, much like how the PHP source does it."

Answer 2

Since you will get an error with newer versions of PHP if the value has a CHAR at the end of it, you might need some extra testing:

private function toBytes($str){
    $val = trim($str);
    $last = strtolower($str[strlen($str)-1]);
    if (!is_numeric($last)) {
        $val = substr($val,0,strlen($val)-1);
        switch($last) {
            case 'g': $val *= 1024;
            case 'm': $val *= 1024;
            case 'k': $val *= 1024;
        }
    }
    return $val;
}

This works with no warnings

Answer 3

even if the solutions above are correct, the switch statement without a break is not very intuitive and for an improved readability, to express what is really going on, I would rather do it this way:

/**
 * @return int maximum memory limit in [byte]
 */
private static function takeMaximumFootprint()
{
    $memory = ini_get('memory_limit');
    $byte = intval($memory);
    $unit = strtolower($memory[strlen($memory) - 1]);
    switch ($unit) {
        case 'g':
            $byte *= 1024 * 1024 * 1024; break;
        case 'm':
            $byte *= 1024 * 1024; break;
        case 'k':
            $byte *= 1024; break;
    }

    return $byte;
}

Answer 4

Or some shorter version, if you please

function toInteger ($string)
{
    sscanf ($string, '%u%c', $number, $suffix);
    if (isset ($suffix))
    {
        $number = $number * pow (1024, strpos (' KMG', strtoupper($suffix)));
    }
    return $number;
}

Answer 5

From the PHP website for ini_get():

function return_bytes($val) {
    $val = trim($val);
    $last = strtolower($val[strlen($val)-1]);
    switch($last) {
        // The 'G' modifier is available since PHP 5.1.0
        case 'g':
            $val *= 1024;
        case 'm':
            $val *= 1024;
        case 'k':
            $val *= 1024;
    }

    return $val;
}

Answer 6

I can only think of a slight variation on what you're doing:

function int_from_bytestring($byteString) {
  $ret = 0;
  if (preg_match('!^\s*(\d+(?:\.\d+))\s*([KMNGTPE])B?\s*$!', $byteString, $matches)) {
    $suffix = " KMGTPE";
    $index = strpos($suffix, $matches[2]);
    if ($index !== false) {
      $ret = $matches[1];
      while ($index--) {
        $matches *= 1024;
      }
    }
  }
  return intval($ret);
}