phpmathnumberssign

Making all numbers negative

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.

Solution

  • 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 :)