Another C++ Question

[LeetViet]

What is this line of code trying to do:

variable = something ? something->somethingelse() : 0;

Sorry, if I'm being vague. I don't know what the ? and : 0 are for.

 

[akubi]

if something is true something->somethingelse() is assigned to variable, otherwise 0 is assigned to it.

 

[Argo]

Originally posted by: LeetViet
What is this line of code trying to do:

variable = something ? something->somethingelse() : 0;

Sorry, if I'm being vague. I don't know what the ? and : 0 are for.

If something isn't null the variable is the result of somethingelse() call on the ojbect pointed to by something. Otherwise it's 0.

 

[statik213]

Originally posted by: LeetViet
What is this line of code trying to do:

variable = something ? something->somethingelse() : 0;

Sorry, if I'm being vague. I don't know what the ? and : 0 are for.

exact same thing as:

if(something)
variable = something->somethingelse();
else
variable = 0;

the ? operator is in a sense a short-hand for an if expression.
It's syntax is something like this:
( condition ? expression : expression)
and can be used anywhere an expression (like (1 + 2) or (x * ( y + z)) ) is required.
Here's how max can be defined w/ ? operator:
int max(int x, int y){
return (x > y) ? x : y;
}

 

[EagleKeeper]

As others stated it is a shorthand notation for a if/then/else statement.

Can make it a pain to read the code and does not make the execution of the code any faster if a decent compiler is used.

 

[dornick]

I prefer the tertiary operator. It looks more compact.

 

[EagleKeeper]

Originally posted by: dornick
I prefer the tertiary operator. It looks more compact.

Try to maintain cute code:thumbsdown:

 

[oog]

I've always called them ternary operators. And I don't think they make the code less readable. The g++ extension that allows self-assignment takes more getting used to. I wouldn't bother using these since they aren't in the standard:

int a = 5, b=4;
a <?= b; // a is assigned the value of b

 

[statik213]

Originally posted by: oog
I've always called them ternary operators. And I don't think they make the code less readable. The g++ extension that allows self-assignment takes more getting used to. I wouldn't bother using these since they aren't in the standard:

int a = 5, b=4;
a <?= b; // a is assigned the value of b

what???? how is that different to a = b?

 

[statik213]

Originally posted by: dornick
I prefer the tertiary operator. It looks more compact.

... and is not anymore difficult to read.... just not as common.

 

[oog]

Originally posted by: statik213

Originally posted by: oog
I've always called them ternary operators. And I don't think they make the code less readable. The g++ extension that allows self-assignment takes more getting used to. I wouldn't bother using these since they aren't in the standard:

int a = 5, b=4;
a <?= b; // a is assigned the value of b

what???? how is that different to a = b?

I wouldn't worry about it too much. It's not in the C++ standard, and I think they were talking about rejecting it from being up into the standard. It's different from assignment because it's a conditional assignment. If a were less than b then the assignment wouldnt' happen. It's the equivalent of this:

a = ((a<b) ? a : b);

or

if (a<b) a=b;

 

[statik213]

Hmmm, interesting, would have only a very limited application....
thx!

 

[Barnaby W. Füi]

Originally posted by: EagleKeeper
As others stated it is a shorthand notation for a if/then/else statement.

Can make it a pain to read the code and does not make the execution of the code any faster if a decent compiler is used.

Anything is a pain to read if you're not used to it. There is nothing inherently hard to read about the ternary operator; in fact I value conciseness a lot, and for that reason I like it.

 

[EagleKeeper]

Originally posted by: BingBongWongFooey

Originally posted by: EagleKeeper
As others stated it is a shorthand notation for a if/then/else statement.

Can make it a pain to read the code and does not make the execution of the code any faster if a decent compiler is used.

Anything is a pain to read if you're not used to it. There is nothing inherently hard to read about the ternary operator; in fact I value conciseness a lot, and for that reason I like it.

Maintainence and documenation need to be considered when writing code.
to many people try and keep code as terse as possible and not indicate reason for logic.

These type of statement unless documented can become a both for someone attempting to maintain the code at a later date.

It can create poor habits down the road, even if the code itself is quality.

 

[Barnaby W. Füi]

Originally posted by: EagleKeeper

Originally posted by: BingBongWongFooey

Originally posted by: EagleKeeper
As others stated it is a shorthand notation for a if/then/else statement.

Can make it a pain to read the code and does not make the execution of the code any faster if a decent compiler is used.

Anything is a pain to read if you're not used to it. There is nothing inherently hard to read about the ternary operator; in fact I value conciseness a lot, and for that reason I like it.

Maintainence and documenation need to be considered when writing code.
to many people try and keep code as terse as possible and not indicate reason for logic.

These type of statement unless documented can become a both for someone attempting to maintain the code at a later date.

It can create poor habits down the road, even if the code itself is quality.

Not indicating "reason for logic" (comments, descriptive names, etc) is an entirely separate issue from using the ternary operator.

if(something)
foo = bar;
else
foo = baz;

foo = something ? bar : baz;

There's nothing that makes the second harder to understand, except an individual's lack of familiarity with the syntax -- and anyone that doesn't understand the ternary operator shouldn't be working on any remotely serious C++ project.

 

[BFG10K]

I prefer the tertiary operator. It looks more compact.

Same here - I like to write as little code as possible and keep things compact. I hate scrolling through pages and pages of redundant code.

 

[LeetViet]

Thanks for all your help and quick responses.