更改PHP中数字的符号? [英] Changing the sign of a number in PHP?

问题描述

我有几个花车:

-4.50
+6.25
-8.00
-1.75

如何将所有这些都更改为负浮点数，以便变为:

How can I change all these to negative floats so they become:

-4.50
-6.25
-8.00
-1.75

我还需要一种相反的方法

Also I need a way to do the reverse

如果浮点为负，则使其为正.

If the float is a negative, make it a positive.

推荐答案

琐碎

$num = $num <= 0 ? $num : -$num ;

或者更好的解决方案，恕我直言:

or, the better solution, IMHO:

$num = -1 * abs($num)

如@VegardLarsen所发布的，

As @VegardLarsen has posted,

可以避免显式乘法的简短性，但我更喜欢可读性而不是简短性

the explicit multiplication can be avoided for shortness but I prefer readability over shortness

我建议避免使用if/else(或等效的三元运算符)，尤其是当您必须操纵多个项目(循环或使用 lambda函数)时，这会影响性能.

I suggest to avoid if/else (or equivalent ternary operator) especially if you have to manipulate a number of items (in a loop or using a lambda function), as it will affect performance.

如果浮点为负，则使其为正."

要更改数字的符号，您只需执行以下操作:

In order to change the sign of a number you can simply do:

$num = 0 - $num;

，或者乘以-1，当然:)

or, multiply it by -1, of course :)

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