在 PHP 中向下舍入到最接近的半整数
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Round DOWN to nearest half integer in PHP
提问by Chris Fletcher
I need a PHP function that will take a float and round it down to the nearest half(x.0 or x.5). I found other functions that will round to the nearest fraction, but they round both ways.
我需要一个 PHP 函数，它将采用一个浮点数并将其四舍五入到最接近的一半（x.0 或 x.5）。我发现其他函数会四舍五入到最接近的分数，但它们都是双向的。
The function I need can only round down.
我需要的功能只能四舍五入。
Examples
例子
7.778 -> 7.5
7.778 -> 7.5
7.501 -> 7.5
7.501 -> 7.5
7.49 -> 7.0
7.49 -> 7.0
7.1 -> 7.0
7.1 -> 7.0
回答by Dominic Rodger
$x = floor($x * 2) / 2;
回答by tzaman
I'm assuming PHP has a floor function: floor($num * 2) / 2ought to do it.
我假设 PHP 有一个地板功能：floor($num * 2) / 2应该这样做。
回答by Berserk
A easy solution is to use modulo operator (fmod()function), like this :
一个简单的解决方案是使用模运算符（fmod()函数），如下所示：
function roundDown($number, $nearest){
return $number - fmod($number, $nearest);
}
var_dump(roundDown(7.778, 0.5));
var_dump(roundDown(7.501, 0.5));
var_dump(roundDown(7.49, 0.5));
var_dump(roundDown(7.1, 0.5));
And the result :
结果：
The advantage it's that work with any nearest number (0.75, 22.5, 3.14 ...)
它的优点是可以使用任何最接近的数字（0.75、22.5、3.14 ...）
You can use the same operator to roundUp :
您可以使用相同的运算符来舍入：
function roundUp($number, $nearest){
return $number + ($nearest - fmod($number, $nearest));
}
var_dump(roundUp(7.778, 0.5));
var_dump(roundUp(7.501, 0.5));
var_dump(roundUp(7.49, 0.5));
var_dump(roundUp(7.1, 0.5));
回答by xavadu
You can do it on that way round($number / 5, 1) * 5the second parameter in the round()is the precision.
你可以这样做，round($number / 5, 1) * 5第二个参数round()是精度。
Example with $numberequal to 4.6, 4.8 and 4.75
$number等于 4.6、4.8 和 4.75 的示例
>>> round(4.6 / 5, 1) * 5;
=> 4.5
>>> round(4.8 / 5, 1) * 5;
=> 5.0
>>> round(4.75 / 5, 1) * 5;
=> 5.0
If you want you can round()down too like round($number, 1, PHP_ROUND_HALF_DOWN)check the documentation for more information https://www.php.net/manual/en/function.round.php
如果你愿意，你可以round()倒也像round($number, 1, PHP_ROUND_HALF_DOWN)检查的详细信息的文档https://www.php.net/manual/en/function.round.php
回答by Kiran
echo round($val*2) / 2; // Done
回答by chuyen nha
From my job's requirements. I put an function to do this. Hope you can view it as a reference:
从我的工作要求来看。我放了一个函数来做到这一点。希望大家可以作为参考：
function round_half_five($no) {
$no = strval($no);
$no = explode('.', $no);
$decimal = floatval('0.'.substr($no[1],0,2)); // cut only 2 number
if($decimal > 0) {
if($decimal <= 0.5) {
return floatval($no[0]) + 0.5;
} elseif($decimal > 0.5 && $decimal <= 0.99) {
return floatval($no[0]) + 1;
}
} else {
return floatval($no);
}
}
