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

User · Answer

using alberT and Dan Tao solution   negative to positive and viceversa   num    num  lt   0   abs  num    - num

User · Answer

A trivial   num    num  lt   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

User · Answer

function invertSign  value        return - value

User · Answer

re the edit   Also i need a way to do the reverse If the float is a negative  make it a positive    number   - number    changes the number to its opposite

User · Answer

function positive number  number        if   number  lt  0             number    -1            return  number

User · Answer

float   -abs  float

User · Answer

How about something trivial like    inverting    num   - num   converting only positive into negative   if   num  gt  0   num   - num   converting only negative into positive   if   num  lt  0   num   - num

User · Answer

I think Gumbo s answer is just fine  Some people prefer this fancy expression that does the same thing    int      int  gt  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      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

[php] Changing the sign of a number in PHP?

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