Absence of if / loop body allowed: example?

Question

I found a few weird constructs in Java that the compiler allows, but for which I'm not sure what could be the practical use.

1) if statement:

if((score=score+10) > 110); //No if body

while eg: switch(++i); is not

2) for loop:

for(;;); //No loop body

Are there practical, valid circumstances to use the preceding code?

it's usually only useful if there are side effects of the expressions within the statements — Alnitak, Feb 14 '16 at 16:47
I was just looking for an example where the code could be useful. I'll delete the question if you think it adds no value. — html_programmer, Feb 14 '16 at 16:48
I have used `while` loops without bodies to completely consume an iterator or `InputStream`. — mihi, Feb 14 '16 at 16:54
@Tunaki well, if you say it is opinion based, I opine that `for(;;);` brings me cakes! — Sнаđошƒаӽ, Feb 14 '16 at 16:58
@mihi but OP's code literally does nothing - the `for` loop has no body — Bohemian, Feb 14 '16 at 16:58
If you wait long enough, and look in enough places, quantum theory says that a unicorn will appear — Bohemian, Feb 14 '16 at 17:03
@Tunaki Not such a stupid question so it seems. http://stackoverflow.com/questions/14112515/semicolon-at-end-of-if-statement http://stackoverflow.com/questions/16428903/empty-if-statements It does appear to be a duplicate though. Also a great example of the SO bandwagon, thanks for your contribution. — html_programmer, Feb 14 '16 at 17:33
Where did I say this was a stupid question really? Because I didn't. I said "Too broad and opinion-based". Which is completely different. — Tunaki, Feb 14 '16 at 17:34

Bohemian · Accepted Answer · 2016-02-14T16:57:41.930

2

This:

if((score=score+10) > 110);

is equivalent to:

score += 10;

but has no practical use otherwise.

This:

for(;;);

loops forever doing nothing - not particularly useful, unless you wanted to create a permanently busy thread perhaps for testing purposes.

edited Feb 14 '16 at 16:57

answered Feb 14 '16 at 16:49

Bohemian

1

You're wrong. for(;;) is the equivalent to while(true) and there are PLENTY of uses for using that. – Luke Xu Feb 14 '16 at 16:52
@LukeXu Except that if you mean "while true" why not say `while(true)`? – Patricia Shanahan Feb 14 '16 at 16:54
2

@Luke `for(;;);` (empty body as per OP Q) it is equivalent to `while(true);` (empty body). No use. – Bohemian Feb 14 '16 at 16:55
@LukeXu FYI, before you judge someone as wrong (especially a high-rep user), there is PLENTY of difference between `for(;;)` and `for(;;);`, which, as said here already, has **no use**. – Sнаđошƒаӽ Nov 29 '16 at 16:15
@Sнаđошƒаӽ FYI, before you judge perhaps you should look at the edit history and then look at the time stamps of the comments. I didn't know reputation made you a good coder. – Luke Xu Nov 29 '16 at 23:36
@LukeXu Apologies, I didn't look at the edit history. But still, I think the initial version was just the result of a typo, not the intention of the answerer. You are right, reputation doesn't make you a good coder, but in most of the cases only good coders make good reputations. I am sure you will agree :-) – Sнаđошƒаӽ Nov 30 '16 at 06:48

1 Answers1