Delete digits after two decimal points, without rounding the value

Question

i have value in php variable like that

$var=\'2.500000550\';
echo $var

what i want is to delete all decimal points after 2 digits.

Answer 1

You're requesting a function that returns "2.50" and not 2.5, so you aren't talking about arithmetic here but string manipulation. Then preg_replace is your friend:

$truncatedVar = preg_replace('/\.(\d{2}).*/', '.$1', $var);

// "2.500000050" -> "2.50", "2.509" -> "2.50", "-2.509" -> "2.50", "2.5" -> "2.5"

If you want to do it with arithmetic, simply use:

$truncatedVar = round($var * 100) / 100);

// "2.500000050" -> "2.5", "2.599" -> "2.59", "-2.599" -> "2.59"

Answer 2

floor(2.500000550 * 100) / 100;

This should do your task...

Answer 3

use sprintf

sprintf("%01.2f", $var);

Answer 4

If you don't want to round the number but you want to remove the decimal places you can use "substr" method

substr(string, start, length);
substr(4.96, 0, -1);

Answer 5

The following is (what I believe is - please correct me if not) a robust mathematical* solution, based mostly on the information from several other answerers here, and a small amount from me

(*Which is not to suggest there's anything wrong with Liphtier's regex-based answer - just that I can see purists wanting to avoid regex for what is arguably a mathematical problem.)

• sprintf(), number_format() (and round(), obviously), are all performing a rounding operation so are not appropriate for the non-rounding truncation requested in the question (not on their own, at least).
• In lieu of an out-of-the-box function, the seemingly most elegant solution was Sujit Agarwal's answer
• But because of the way floats are stored, we need to use an epsilon - as pointed out in David Constantine's answer (where he also makes the previous solution more general by using pow() to get the right factor based on a specified precision).
• But then, as pointed out in cale_b's answer, any use of floor() (or presumably ceil()) may produce unintended results for negatives without use of abs().
• And the value I'm trying to add is:
  • If using a division on abs() to get a negation factor, we need to account for the special case when the input is 0.
  • We should dynamically create the epsilon; A static hard-coded epsilon might be too small or too large, depending on the precision required. I haven't seen this issue addressed in the other answers.

The code I'm using is:

public static function truncate_decimal($number, $leavePlaces = 2)
{
    if ($number == 0) return 0;
    $negate = $number / abs($number);
    $shiftFactor = pow(10, $leavePlaces);
    $epsilon = pow(10, -1 * $leavePlaces);
    return floor(abs($number) * $shiftFactor + $epsilon) / $shiftFactor * $negate;
}

Answer 6

someone posted here about

floor(2.500000550 * 100) / 100;

function cutAfterDot($number, $afterDot = 2){
$a = $number * pow(10, $afterDot);
$b = floor($a);
$c = pow(10, $afterDot);
echo "a $a, b $b, c $c<br/>";
return $b/$c ;
}
echo cutAfterDot(2.05,2);

a 205, b 204, c 100
2.04

so in raw form don't use it... But if you add a little epsilon...

function cutAfterDot($number, $afterDot = 2){
        return floor($number * pow(10, $afterDot) + 0.00001) / pow(10, $afterDot);
    }

it works!