post/pre-increment/decrement A.K.A. ++ - -

[colton peterson]

what is the difference between i++ and ++i?

if i = 1; then wouldn't the both make I equal 2?

[Jeanne Boyarsky]

Yes and if you have them as a command by themselves, they work the same. If you have them in a command that also does something else, you get different results because they increment/decrement at different times.

Try running the following code:

int i = 1;
System.out.println(i++);
i = 1;
System.out.println(++i);

They give different results because they increment at different times.

[colton peterson]

it said

1
2

process complete

so i++ returns the value and then increments
and ++i increments the value then returns

right?

[Jeanne Boyarsky]

Originally posted by colton peterson:
so i++ returns the value and then increments
and ++i increments the value then returns

Right!

[Ilja Preuss]

Originally posted by colton peterson:

so i++ returns the value and then increments
and ++i increments the value then returns

Not exactly.

Both actually increment the value of i *first*, and then return. The difference is that i++ returns the value i had before the increment, ++i returns the value i has after the increment.

That is why

i = i++;

doesn't change the value of i at all. Or more precisely, it first increments the value of i, and then sets it back to the old value.

[colton peterson]

Thanks!