What is the name of this operator: “--”?

The_Egg_Man wrote: post #3

Could someone break this down and explain it to me? [1] It looks hilariously atrocious yet interesting at the same time. [1]: http://stackoverflow.com/questions/1642028/what-is-the-name-...

  #define as ;while
  ...
  do printf("n is %d\n", n) as ( n --> 0);

Parses to (white space adjusted for clarity):

  do printf("n is %d\n", n);
  while ( n-- > 0);

Re: What is the name of this operator: “--”?

#5

Post by dmbass » Tue, Oct 23, 2012, 2:45 AM UTC

The_Egg_Man wrote: post #3

Could someone break this down and explain it to me? [1] It looks hilariously atrocious yet interesting at the same time. [1]: http://stackoverflow.com/questions/1642028/what-is-the-name-...

The preprocessor replaces the macro "as" with ";while" creating a do-while loop.

  do {
   printf("%d",x);
  } while (x-- > 0);

Re: What is the name of this operator: “--”?

#6

Post by sukuriant » Tue, Oct 23, 2012, 2:53 AM UTC

This looks mostly like a function that sacrificed readability for brevity, to the detriment of at least one reader.

Re: What is the name of this operator: “--”?

#7

Post by halis » Tue, Oct 23, 2012, 2:57 AM UTC

Decrement x = x -1

Re: What is the name of this operator: “--”?

#8

Post by stephen_g » Tue, Oct 23, 2012, 3:04 AM UTC

The_Egg_Man wrote: post #3

Could someone break this down and explain it to me? [1] It looks hilariously atrocious yet interesting at the same time. [1]: http://stackoverflow.com/questions/1642028/what-is-the-name-...

Basically, somebody sees some code with two operators (decrement and less than) with no whitespace between them and thinks it's a single operator.

The answer that shows it with the brackets is probably the clearest:

    while ((x--) > 0)
    { ... }

The compiler sees that as the same as (x--> 0)

So it checks if x is more than zero and then decrements it each loop iteration.

Re: What is the name of this operator: “--”?

#9

Post by QuarkSpark » Tue, Oct 23, 2012, 3:12 AM UTC

rwolf wrote: post #2

The title is missing a >. Should be "-->"

For some reason it changes the "-->" back to "--" I tried many times/ways to include the entire operator before giving up & just posting it..

Re: What is the name of this operator: “--”?

#10

Post by sukuriant » Tue, Oct 23, 2012, 4:39 AM UTC

QuarkSpark wrote: post #9

rwolf wrote: post #2

The title is missing a >. Should be "-->"

For some reason it changes the "-->" back to "--" I tried many times/ways to include the entire operator before giving up & just posting it..

What about > ?