Changing the sign of a number in PHP?


Question

I have a few floats:

-4.50
+6.25
-8.00
-1.75

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

-4.50
-6.25
-8.00
-1.75

Also I need a way to do the reverse

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

1
55
2/10/2018 2:42:04 PM

Accepted Answer

A trivial

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

or, the better solution, IMHO:

$num = -1 * abs($num)

As @VegardLarsen has posted,

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

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.

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

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

$num = 0 - $num;

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

147
2/10/2018 2:43:22 PM

$float = -abs($float);

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