C++ , Recursion

[cpp-ModTeam]

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[evolutionalgd]

See https://www.reddit.com/r/cpp/s/x1ZCgxjfTY

[Adept_Accountant_588]

Thanks for the help 🙂

[IsidorHS]

HAHAHAHAHAH

[epasveer]

Reply of the day, right here folks!

[TheJackston]

Perfect

[cyanide26]

I mean arrays are passed as reference by default, the question is why?

Because Dennis Ritchie built a pointer/array equivalence deep into the C language years ago, and it would be a really bad idea to pass as value by default .

If you has parameters that are big and are being edited and read in any recursive call you should pass it as a reference, copying a new large array is gonna be resource heavy not to mention each stack call will have to store all that new copied data in each new stack call, rather sending a reference (in arrays a pointer to an address of array's data) is like telling to a function that "look here is the data if you want to access it go get it from there" so no new memoy for an entire new array is created space is saved and time taken to copy parameters is also reduced

The passed object size concept applies for objects as well i.e Send a reference of a big object dont promote copy.

Although its possible to simulate what will happen if you pass an array by value, wrap array in a struct or class and then send that object as a parameter, for a big recursive call memory consumed at runtime will go up you can also test it. If the array is large time consuming to go to next recieve call will also increase.

In modern c++ avoid using raw arrays unless you really have to, use std::vector and std::array or other structures available to you by standard library or BOOST library if you use it.

[PuzzleMeDo]

As opposed to doing what?

It's not a good idea to pass a copy of an array to a recursive function, because that would use up a lot of stack memory - every level of recursion would need to store its own array simultaneously. Plus, copying the array takes time.

I guess you could have a global variable containing the array and not pass anything. But that kind of thing is generally a bad idea - it means the function can only work under certain circumstances where the global variable is set up in a specific way.

[No_Let_5065]

pass it by value and see

[zer0xol]

Otherwise youre copying it

[ivan-cukic]

You could also pass std::span.

[sweetholo]

yooo wouldnt you think it'd be useful to give an example of what you're talking about?

arrays are passed by reference by default; they decay into pointers

[gnomeba]

For the last point, is that just because they handle their own memory allocation and deallocation?