What does n*=-1 mean in Java? Particularly n*=

Question

so I'm supposed to read a code and I don't understand what this notation means. I understand that n+= bla, means n+1= bla. But i can't make out the meaning of n*= -1. Can someone tell me real quick. Also does anyone know WHY this would be used instead of a clearer notation? Whoever wrote the code couldn't have possibly saved more than a few letter when using this...

Answer 1

n += bla is equivalent to n = n + bla

n *= -1 is equivalent to n = n * -1

There's no functional reason to choose one notation over the other, it's just a stylistic preference. Java language (and others as well) is full of equivalent statements:

n++ is equivalent to n=n+1

n=m=1 is equivalent to n=1; m=1; n=1; m=1;

and many many others

Answer 2

n*= -1 does same thing as: n = n* -1

In Java or C++, there are things like:

+=, -=, *=, /=, &=, |=

They are all the same in a sense.

That is, do the operation first, then do the assignment.

Answer 3

It's the compound assignment operator version of the multiplication operator.

The code n *= x is equal to n = n * x So in your case, n *= -1 would make n equal to itself multiplied by -1.

The only difference between using the compound assignment operator and the normal assignment operator with a multiplication expression is of stylistic preference.

You can read about compound assignment operators here: http://java.about.com/od/c/g/compoundassgnment.htm

Answer 4

It means n = n*(-1). Just changing the sign.

Answer 5

n += bla is the same as n = n + bla

n *= -1 is the same as n = n * -1

All of these operators act the same way : value math-operator assignment-operator other value is the same as value assignment-operator value math-operator other value