在PHP中为浮点数设置精度

问题描述

我从数据库中获得了一个号码，这个号码可能是float或int.

我需要将数字的小数精度设置为3，这使得数字不超过(关于小数)5.020或1518845.756.

I get a number from database and this number might be either float or int.

I need to set the decimal precision of the number to 3, which makes the number not longer than (regarding decimals) 5.020 or 1518845.756.

使用PHP

round($number, $precision)

我看到一个问题:

将数字四舍五入.我需要一个仅将小数点缩短而不更改round( )似乎不遵循的值的函数.

It rounds the number. I need a function to only cut the decimals short, without changing their values which round( ) seems not to follow.

推荐答案

您可以使用 number_format() 来实现这个:

You can use number_format() to achieve this:

echo number_format((float) $number, $precision, '.', '');

这会将1518845.756789转换为1518845.757.

但是，如果您只想将小数位数减少到3个，并且 不舍入，则可以执行以下操作:

But if you just want to cut off the number of decimal places short to 3, and not round, then you can do the following:

$number = intval($number * ($p = pow(10, $precision))) / $p;

乍一看可能令人生畏，但是这个概念确实很简单.您有一个数字，将其乘以10 (它变为1518845756.789)，将其强制转换为整数，以便删除小数点后3位后的所有内容(成为1518845756)，然后除以结果减去10 (成为1518845.756).

It may look intimidating at first, but the concept is really simple. You have a number, you multiply it by 10 (it becomes 1518845756.789), cast it to an integer so everything after the 3 decimal places is removed (becomes 1518845756), and then divide the result by 10 (becomes 1518845.756).

演示

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