Question

This is probably a very trivial question, but..

Assuming we have a variable ‘a’ that has a value of 10

Then we have a variable ‘b’ that has a value of 5

Can I remove the value of ‘b’ from ‘a’ (leaving 5) and change the value of a each time?

In my head I think of it as:

a - b = 5

a - b = 0

a - b = -5

etc etc..

Thanks!

Answer 1

Consider this:

a = 10
b = 5
a = a - b 

Now the value of a is 5. This is because Ruby evaluates what is on the right side of the assignment operator = first and then assigns that value to whatever is on the left side.

#Another way to put it
a = (a - b)

There is also a shortcut since this type of math is very common

a = a - b
a -= b
# These are both the same

If you want to do this a certain number of times, try a loop.

a = 10
b = 5
3.times do {a -= b}
# a is now -5

For further basic Ruby learning, I would suggest Try Ruby to get you started on concepts as I mentioned above. (Type “next” there to get started)