在 PHP 中更改数字的符号？
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Changing the sign of a number in PHP?
提问by dotty
I have a few floats:
我有几个浮点数：
-4.50
+6.25
-8.00
-1.75
How can I change all these to negative floats so they become:
我怎样才能将所有这些更改为负浮点数，使它们变为：
-4.50
-6.25
-8.00
-1.75
Also I need a way to do the reverse
我也需要一种方法来做相反的事情
If the float is a negative, make it a positive.
如果浮点数为负数，则将其设为正数。
回答by drAlberT
A trivial
一个琐碎的
$num = $num <= 0 ? $num : -$num ;
or, the better solution, IMHO:
或者，更好的解决方案，恕我直言：
$num = -1 * abs($num)
As @VegardLarsen has posted,
正如@VegardLarsen 所发布的，
the explicit multiplication can be avoided for shortness but I prefer readability over shortness
为了简洁可以避免显式乘法，但我更喜欢可读性而不是简短
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.
我建议避免 if/else（或等效的三元运算符），特别是如果您必须操作多个项目（在循环中或使用lambda 函数），因为它会影响性能。
"If the float is a negative, make it a positive."
“如果浮动是负数，那就让它变成正数。”
In order to change the sign of a number you can simply do:
为了更改数字的符号，您可以简单地执行以下操作：
$num = 0 - $num;
or, multiply it by -1, of course :)
或者，乘以-1，当然:)
回答by Vegard Larsen
$float = -abs($float);
回答by Gumbo
How about something trivial like:
一些琐碎的事情怎么样：
inverting:
$num = -$num;converting only positive into negative:
if ($num > 0) $num = -$num;converting only negative into positive:
if ($num < 0) $num = -$num;
反转：
$num = -$num;仅将正数转换为负数：
if ($num > 0) $num = -$num;仅将负值转换为正值：
if ($num < 0) $num = -$num;
回答by SilentGhost
re the edit: "Also i need a way to do the reverse If the float is a negative, make it a positive"
重新编辑：“我还需要一种方法来做相反的事情如果浮动是负数，则将其设为正数”
$number = -$number;
changes the number to its opposite.
将数字更改为相反的数字。
回答by Dan Tao
I think Gumbo's answer is just fine. Some people prefer this fancy expression that does the same thing:
我认为 Gumbo 的回答很好。有些人更喜欢这种做同样事情的花哨表达：
$int = (($int > 0) ? -$int : $int);
EDIT: Apparently you are looking for a function that will make negatives positive as well. I think these answers are the simplest:
编辑：显然你正在寻找一个函数，它也会使底片变成正片。我认为这些答案是最简单的：
/* I am not proposing you actually use functions called
"makeNegative" and "makePositive"; I am just presenting
the most direct solution in the form of two clearly named
functions. */
function makeNegative($num) { return -abs($num); }
function makePositive($num) { return abs($num); }
回答by Wallace Maxters
function positive_number($number)
{
if ($number < 0) {
$number *= -1;
}
return $number;
}
回答by Frederik Krautwald
function invertSign($value)
{
return -$value;
}
回答by Marco Limas
using alberT and Dan Tao solution:
使用 alberT 和 Dan Tao 解决方案：
negative to positive and viceversa
从负到正，反之亦然
$num = $num <= 0 ? abs($num) : -$num ;
