Whats the differnce?!

Question

Why is x-1 mit true?? Its 42-1
If I use x-- its 42-1

What's the differnce?

Answer 1

You can't just write x-1, you would have to write x = x -1
x-- is shorthand for the above.

Answer 2

not only that. what really is -- or ++ is a decrement or increment operator respectively. you can have pre or post increment operator, something you cannot do easly and clear with only "a += 1". Preincrement operator first increment and then make uae of the thing, so for example:
a = 2
print(++a)

will result in printing 3, because incrementation is Pre, means it is done first, then everything else goes on. For the post incrementation, take a look:
a = 2
print(a++)

will result in printing 2, and a will equal 3 but after it is prined.
Hope it makes some things clear!