PHP dropping decimals without rounding up

Question

I want to drop off decimals without rounding up. For example if I have 1.505, I want to drop last decimal and value should be 1.50. Is there such a function in PHP?

Answer 1

To do this accurately for both +ve and -ve numbers you need use:
- the php floor() function for +ve numbers
- the php ceil() function for -ve numbers

function truncate_float($number, $decimals) {
    $power = pow(10, $decimals); 
    if($number > 0){
        return floor($number * $power) / $power; 
    } else {
        return ceil($number * $power) / $power; 
    }
}

the reason for this is that floor() always rounds the number down, not towards zero.
ie floor() effectively rounds -ve numbers towards a larger absolute value
eg floor(1.5) = 1 while floor(-1.5) = -2

Therefore, for the multiply by power, remove decimals, divide by power truncate method :
- floor() only works for positive numbers
- ceil() only works for negative numbers

To test this, copy the following code into the editor of http://phpfiddle.org/lite (or similar):

Php Truncate Function


 0){
            return floor($number * $power) / $power; 
        } else {
            return ceil($number * $power) / $power; 
        }
    }

    // demo
    $lat = 52.4884;
    $lng = -1.88651;
    $lat_tr = truncate_float($lat, 3);
    $lng_tr = truncate_float($lng, 3);
    echo 'lat = ' . $lat . '
';
    echo 'lat truncated = ' . $lat_tr . '
';
    echo 'lat = ' . $lng . '
';
    echo 'lat truncated = ' . $lng_tr . '

';

    // demo of floor() on negatives
    echo 'floor (1.5) = ' . floor(1.5) . '
';
    echo 'floor (-1.5) = ' . floor(-1.5) . '
';
?>