PHP Round 函数 - 最多舍入 2 dp？

Question

In PHP how would i round up the value 22.04496 so that it becomes 22.05? It seems that round(22.04496,2) = 22.04. Should it not be 22.05??

Thanks in advance

Answer 1

you can do it using ceil and multiplying and dividing by a power of 10.

echo ceil( 1.012345 * 1000)/1000;

1.013

Answer 2

Do not do multiplication inside a ceil, floor or round function! You'll get floating point errors and it can be extremely unpredictable. To avoid this do:

function ceiling($value, $precision = 0) {
    $offset = 0.5;
    if ($precision !== 0)
        $offset /= pow(10, $precision);
    $final = round($value + $offset, $precision, PHP_ROUND_HALF_DOWN);
    return ($final == -0 ? 0 : $final);
}

For example ceiling(2.2200001, 2) will give 2.23 .

Based on comments I've also added my floor function as this has similar problems:

function flooring($value, $precision = 0) {
    $offset = -0.5;
    if ($precision !== 0)
        $offset /= pow(10, $precision);
    $final = round($value + $offset, $precision, PHP_ROUND_HALF_UP);
    return ($final == -0 ? 0 : $final);
}

Answer 3

I think the best way:

echo ceil(round($value * 100)) / 100;

Example:

$value = 77.4;
echo ceil($value * 100) / 100; // 77.41 - WRONG!
echo ceil(round($value * 100)) / 100; // 77.4 - OK!

Answer 4

The round function of PHP can handle an additional argument, which controls how the rounding is done: http://php.net/manual/en/function.round.php

Examples from the link:

echo round(9.5, 0, PHP_ROUND_HALF_UP);   // 10
echo round(9.5, 0, PHP_ROUND_HALF_DOWN); // 9
echo round(9.5, 0, PHP_ROUND_HALF_EVEN); // 10
echo round(9.5, 0, PHP_ROUND_HALF_ODD);  // 9

Answer 5

It's not working well.

round(1.211,2,PHP_ROUND_HALF_UP); 
// Res: 1.21

My Solution:

$number = 1.211;

echo myCeil($number,2);

function myCeil($number,$precision = 0){
    $pow = pow(10,$precision);
    $res = (int)($number * $pow) / $pow;
    
    if($number > $res){
        $res += 1 / $pow;
    }
    return $res;
}
// Res 1.22

Answer 6

Why should it be 22.05 ? The third decimal is less than 5 , hence when you round it to 2 decimal precision it's rounded down to 22.04