since Integer.MAX_VALUE+1==Integer.MIN_VALUE+1, how long will this loop run(sounds like a dumb question but its not)?

Question

for (int x=0 ; x != 0 ; x++) {}

(A) will the loop run 4 billion times because x will start at 0 then approach max value (2^31-1)

(B) will the loop run 2 billion times because x will approach max value then an error will appear

(C) will it run forever because x will approach infinity

Pretty sure the condition is evaluated first and it won’t run at all. Why don’t you test it out? — Solace, Oct 02 '18 at 03:54
Your correction has completely changed the question. That's not allowed! It invalidates the previous Answers. Don't do it. — Stephen C, Oct 02 '18 at 04:18
(And you don't need to @talex's answer already gives the answer to the question that you meant to ask.) — Stephen C, Oct 02 '18 at 04:20
yeah sorry, I realized I wrote the question wrong, sorry for the inconvenience — sandro Hakim Arrangements, Oct 02 '18 at 04:42

score 1 · Accepted Answer · answered Oct 02 '18 at 04:05

1

It won't loop at all.

You initialize x = 0 and then check x != 0. So loop will ends immediately.

If you initialize x = 1 then you get "2^32-1" iterations.

answered Oct 02 '18 at 04:05

talex

Stephen C · Answer 2 · 2018-10-02T04:15:28.660

The loop body will run exactly zero times. On the first iteration, x != 0 will be false.

In the general case of a for loop:

for (<initializations>; <condition>; <post> ) {
    <body>
}

the execution sequence is:

(A) will the loop run 4 billion times because x will start at 0 then approach max value (2^31-1)

Nope. The arithmetic is wrong. 2^31-1 is not 4 billion. It is a bit over 2 billion.

(B) will the loop run 2 billion times because x will approach max value then an error will appear.

Nope. Integer overflow in Java doesn't raise an error / exception.

(C) will it run forever because x will approach infinity

Nope. It wouldn't approach infinity. An int value cannot be larger than Integer.MAX_VALUE

oops it was supposed to be 1, sorry i shoukd have reviewed – sandro Hakim Arrangements Oct 02 '18 at 04:15 — sandro Hakim Arrangements, Oct 02 '18 at 04:15

2 Answers2