Learn the basics

Read it

well you can not. The arr will get deleted when it goes out of scope

this is why

will it pass the compilation

we told you 5 times you cannot do that. Now believe us and never write code like that :-)

will it pass the compilation

most likely yes

will it pass the compilation

Yes

auto func() { std::array array_to_return = {1, 2, 3}; return array_to_return; }

u forgot include type for std::array :)

we told you 5 times you cannot do that. Now believe us and never write code like that :-)

I know that it is silly to do that and I won't do that. but just wanted to ask whether it will pass the compilation. that's it

I know that it is silly to do that and I won't do that. but just wanted to ask whether it will pass the compilation. that's it

Yay

Yes

Thanks for it.

we told you 5 times you cannot do that. Now believe us and never write code like that :-)

wanna see an array with smart pointer ? xDD

u forgot include type for std::array :)

I think it's obvious :)

I know that it is silly to do that and I won't do that. but just wanted to ask whether it will pass the compilation. that's it

Don't use c-style arrays at all

wanna see an array with smart pointer ? xDD

no

:-)

how does return by value work

first the copy of the returned value is made and then returned and the original value is deleted.

Is that right?

Is that right?

Return by value is the simplest and safest return type to use. When a value is returned by value, a copy of that value is returned to the caller. As with pass by value, you can return by value literals (e.g. 5), variables (e.g. x), or expressions (e.g. x+1), which makes return by value very flexible.

int* fun(){ int arr[] = {1,2,3}; return arr; } int* fun(){ int arr[] = {1,2,3}; return (int*)arr; }

So, these are return by address. Right?

Also, I read that When not to use return by value: When returning a built-in array or pointer (use return by address) When returning a large struct or class (use return by reference)

.

how does return by value work

I guess you mean pass by value

No. return

by value

not pass

Well

So, these are return by address. Right?

There's no such thing as "return by address". Your function declaration defines the return type to be a pointer to int. Your array decays to a pointer when used as parameter or return type

https://www.learncpp.com/cpp-tutorial/74a-returning-values-by-value-reference-and-address/

There's no such thing as "return by address". Your function declaration defines the return type to be a pointer to int. Your array decays to a pointer when used as parameter or return type

That's what return by address.

Well The function returns the bare value which is not a reference or a pointer to a memory location

I read that a copy is returned

That's what return by address.

It returns a pointer

copy of the value to be returned.

It returns a pointer

yes

It always return a copy of a something

No matter what

OK.

The real talk is What copy is returned

A reference or a Pointer or a value

can return by address be used to safely return local static members

?

If it's a reference or a pointers The refered/pointed location must be valid after the function call ends

Or it's ub

can return by address be used to safely return local static members

Yes

As long as the static member is valid

But not the vise versa

what scope do local static variables fall in? Are they destroyed after exiting from function?

what scope do local static variables fall in? Are they destroyed after exiting from function?

iirc, static variables are variables that is meant to be existed till the program finishes its execution

But Static member function can't use non-static members

Because static members are instantiated without the need of constructing an object

iirc, static variables are variables that is meant to be existed till the program finishes its execution

Correct, "static storage duration: The storage for these entities shall last for the duration of the program" [basic.stc.static]

Correct, "static storage duration: The storage for these entities shall last for the duration of the program" [basic.stc.static]

Oh, olli hi :D

are class static varaibles have same lifetime as that of local storage variables?

are class static varaibles have same lifetime as that of local storage variables?

Nope

OK so local storage have lifetime as same as that of the program?

Local variables are limited to the lifetime of the object that created them

Unless they are not allocated on the heap

is any one doing 30 days challeng in hacker rank??

Or the destructor failed to be called

how can i pass the hidden test cases??

OK so local storage have lifetime as same as that of the program?

No

are class static varaibles have same lifetime as that of local storage variables?

Absolutely not, they have an initialization check and if not initialized they get initialized

You have to pass all the test cases

i use java for competitive programming i want to switch to c++ can anyone one send me link to a tutorial which can teach me c++

You should write code that matches the specification and it should pass all of them

OK so local storage have lifetime as same as that of the program?

Block-scope Variables have an automatic storage duration and are valid until the block, they were initialized in, ends

yes

Absolutely not, they have an initialization check and if not initialized they get initialized

And they are not cleaned up until exit is called

The hidden test cases are just hints at what special cases your code is failing at

send me the link

Srihari i will help you

i use java for competitive programming i want to switch to c++ can anyone one send me link to a tutorial which can teach me c++

anyone please help me for this

You should write code that matches the specification and it should pass all of them

oo thanks for the reply

And they are not cleaned up until exit is called

Doesn't exist function terminate the program without freeing resources?!🤔

i use java for competitive programming i want to switch to c++ can anyone one send me link to a tutorial which can teach me c++

☝️☝️☝️☝️☝️

☝️☝️☝️☝️☝️

Read bjarne's book

☝️☝️☝️☝️☝️

There are a lot of information on the web to learn cpp. A good place to start can be https://en.cppreference.com/w/