How to Deal with Multiple Return Values in C++

Totally out of my league at this time .

This video seems a bit outdated even with respect to C++ 17, maybe it could be good to make an updated remake. Maybe when C++ 23 is out (idk if it has an impact on this).

Al those fancy C++ methods only to return to plain old C-struct.

I learned some new things! Nice video.

why you fold your legs, we want see your nuts

Q. Why do you not use it much yourself? Return via. structs and pass by ref?

For std::tuple, what about putting enum ShaderType outside ParseShader(), then doing this::

auto sources = ParseShader("res/shaders/Basic.shader");

unsigned int shader = CreateShader(std::get<ShaderType::VERTEX>(sources), std::get<ShaderType:: FRAGMENT>(sources));

I actually like using the struct more because it's organized and easy to read
and also using vector

using tuple maybe I didn't get so I kinda hate it since i follow the series of openGl

I like hearing you talk about memory stuff and by extension performance. I am very likely to never professionally work in c++ but much more likely to use Java. And while I don't need to know all this, I always do better if I can "get under hood." So while what your saying doesn't definitively apply to Java, it helps me understand why Java does what it does and how it does it and knowing that will help me grok the whole thing better.

What IF I want to return only one value, but it being one of two types?

Say a string OR a bool?

I use std::variant for this.

So... back to old fashion C style structs..... or like in Golang. Yeah... but the {a,b} part makes it C++ nicer.

I prefer the struct approach as well, self documenting .

A very nice video, explanation. I would like to mention that if you are precise, the function that takes non const reference as argument and return nothing is the most performance friendly.

I think the most optimised way would be to return a uintptr_t[] which will contain pointers to any values you want to return

When struct is returned by value does that mean that it is first created inside the function and then copied when returned to calling function? Is it better to return it as a reference?

Why did you make it so difficult to understand? Couldn't you start from a empty code?

The fast way…
_asm_ (“mov Var1Reg, %%eax;”
“mov Var2Reg, %%ebx;”);
With an ASM function call on the other side to manage placing them where they need to be (or you can just place them there as your return if you know where you want them beforehand) Pretty ugly, but should be very fast because it can keep most of you data types in registers instead of pushing them to the stack

This could be a poor choice of registers because it’s been a little while since I’ve worked with x86 assembly, but you can find that information from plenty of data sheets online if you are actually doing it this way.

Your code is hard to comprehend. I don't like your explanation

I like your way too.

One thing I don't get, is in the return he initialized a struct but the struct had no parametised constructor?

Personally I prefer to use std::tuple<> and using std::tie() to organize return values. Or using auto [a, b, c, d] = get_data();, but unfortunately I'm not allowed to use this, because I'm tied and required to use C++11

I think using struct is better to deal with multiple return values instead of using tuple.

This is the kind of stuff I'm talking about when I tell people how much I dislike C++.
Why does everything always have to be so unclear to read?

I agree that creating a wrapper struct is the best way to go because it makes everything 100% clear, but why do we have to do that? It's CRAZY when there already exists ways to implement this, but they are so poorly designed that it makes our code less readable.

C# has tuples too, and in C# you can easily access the members just like a pair, but if you don't like to use .first and .second, YOU CAN PROVIDE WHATEVER CUSTOM NAMES YOU WANT.

Creating a custom return type in C# just because you want to return 2 strings with readable names is CRAZY because the functionality is already there and it already provides you with ways to easily make it all 100% clear and readable.

C++ really drives me up the wall...

Structured binding is now a thing in C++17.

Wow I'm absolutely fucking lost

Yes to structs.

Setup's nice - your couch ugly, though... It should be black leather with a tiny scared chick on it.

Other methods of returning multiple values? Well, you could use a loopback socket....

Don't do that tho. XD

Honestly, when I find myself thinking about busting out a tuple I usually just step back and try to figure out where my design went wrong.

Hey Cherno, love your videos! In last part where you explained struct is the best way to return two values, how did it work by just returning { vs, fs} without allocating it into the heap?

In python you can automatical... automagically ...

LOL

I prefer the strict approach

I think for generic stuff, pair and tuple is fine, though tuple syntax slightly clunky, and feel triple and quads should be a standard thing. For stuff used a lot, struct makes sense, but if I have a function called once or twice, I would just use a pair. Pass by reference would be the fastest, and preferred way in performance critical sections, but I don't like cluttering up function call if don't need performance.

For anyone reading recently, there's a better way with structured binding since c++17:

Return a tuple of your choice and return it as per the video:
std::tuple<std::string, std::string, int> getData() {
return { "One", "two", 3 };
}
Retrieve values using structured binding:
auto [str1, str2, number] = getData();

Me: It's pretty annoying that you can only ever return one thing...
Cherno: Yeah so here's about 10 different ways off the dome you can do this 🤯
And that's why I'm here, to learn this stuff!

IMHO structs are the most natural and reliable way of handling functions with rich returns. Funnily enough that what I see most people who are not this advanced in c++ do. I feel like some very experienced people sometimes do things syntactically more complex just for sake of showing of 😃

Sorry, but the explanation is very messy and incoherent :(

Hi, if std::array allocates memory on stack, how do you return it then?

The struct.... Just the struct .... The others are just noo........

Ironically it's quite simple for a compiler to compile multiple returns down to an anonymous struct and pass the values into the chosen variables so this: "a, b, c = func()" would compile down to roughly "push push push call func mov c +3 mov b +2 mov a +1 pop pop pop" (though in a more assembly friendly then that)

After learning python c++ is so annoying XD

Hey! , Why an OpenGL video is on C++ Series??, Is this part of C++ Series

Im skipping this one

Thank you so much for your indepth coverage of coding styles. As someone new to code you are making understanding c++ a very enjoyable experience.

Great Job Cherno!

Structs

My favorite ways are 1. Passing by Reference and 2. Using the struct.
Nice video thanks!

I wonder how he felt like after he stopped recording and realised that tuple is in tuple header file
(not hating he said he doesn't use it as often)

Why can't we create a static array and return it in a function with a return type of array? Please help. Thanks.

Want to return 2 32 bit integer while only returning 1 value?
put the first value in a 64-bit integer and shift it left by 4 bytes so it occupies the 32 most significant bits.
Put the second value in a 64-bit integer so it occupies the 32 least significant bits.
Return the OR of these two.

Now to get your two 32-bit values back just AND the returned value with 0xFFFFFFFF00000000 and 0x00000000FFFFFFFF respectively.

For the record I don't advice doing this