How can I declare an "extern" full specialization of function template in header file?

I don't get it

I was asked in an interview, say i need to create a new object of the concrete type to which the base pointer points to. How to do that ? I gave 2 obvious options of dynamic_cast and typeid but he said both will need if-else. Any one know of any other method ?

You need to use polymorphism. Create a virtual method called clone which returns a unique_ptr<Base> in the base class and a unique_ptr<Derived> in the derived class. So if you use a pointer or a reference to the base to call the clone method, the correct virtual method will be called depending on the object being pointed to.

You can read books about functional programming, they will help you to better understand some functional design patterns including recursion.

??? Functional programming uses recursion as a very basic tool. There are more advanced concepts in functional programming than recursion like monoids, monads, functors, ADTs and so on many of which actually dont require recursion and can be implemented using pattern matching on type/data constructors and composition. Asking someone to study functional programming to learn recursion is like asking someone trying to understand how a while loop in python works to learn C++.

You need to use polymorphism. Create a virtual method called clone which returns a unique_ptr<Base> in the base class and a unique_ptr<Derived> in the derived class. So if you use a pointer or a reference to the base to call the clone method, the correct virtual method will be called depending on the object being pointed to.

Understood. Let me try a sample and get back if any doubts. Thanks

In the main ? You don’t but it’s a good practise to write return something

That's actually an interesting question, do people generally return 0 from main or not

That's actually an interesting question, do people generally return 0 from main or not

If you dont, then use void main instead of int main.

If you dont, then use void main instead of int main.

No, that's not portable

No, that's not portable

To where?

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#f46-int-is-the-return-type-for-main

To anywhere outside MSVC

I use gcc/g++ it works fine

I use gcc/g++ it works fine

It doesn't compile for me 🤷‍♂️ https://wandbox.org/permlink/ScknknFlZYgRWe9T

No it's not int main(void) { } Compile with -pedantic-errors, it wouldn't compile

No it's not int main(void) { } Compile with -pedantic-errors, it wouldn't compile

What compiler do you use? Both GCC and clang compile it for me with this flag https://wandbox.org/permlink/IRalLucHWwaI1DDt

What compiler do you use? Both GCC and clang compile it for me with this flag https://wandbox.org/permlink/IRalLucHWwaI1DDt

Okay sorry, my memory got rusty. I think i remember it wrong.

If you dont, then use void main instead of int main.

main should return int

I think the compiler wont compile if it void main() or missing return type. It's not empty main() func

No, that's the standard

You should check if it standards or not with pedantic flag

main function should return int.

Of course GCC will compile also but it also generates warn

MSVC just were adding stuff to their compiler that allowed some incorrect code to compile or work

MSVC just were adding stuff to their compiler that allowed some incorrect code to compile or work

Bruh

volatile

the main function is actually an exception in C11

not returning anything from int main implies return 0, as C11 standard implies

Thanks for the information

Doesn’t apply to anything else, including WinMain

but it generates warn

Not in msvc. But not sure about standard

How can I declare an "extern" full specialization of function template in header file?

Your question is confusing. Do you want to generate a specific instantiation in one translation unit and mark it as extern in a header file to prevent instantiations in other translation units? Or do you want to write a specialization for specific types for your function template? When you specialize, you cant mark it as an extern template elsewhere.

🤔

I would be very grateful if you help me, find my problem in the Daysandbox report (-> ???)

I would be very grateful if you help me, find my problem in the Daysandbox report (-> ???)

Hello! I'm quite new to the world of C. I should compile a repository found on github but I can not configure the codeblocks compiler, the developer in read.md said that it uses the compiler "mingw-7.3.0", I tried to use the automatic installation provided in the installations of codeblocks, to manually install the compiler and declare the files in the toolchain but unfortunately I did not produce any results

(it treats read.md as link)

Hello! I'm quite new to the world of C. I should compile a repository found on github but I can not configure the codeblocks compiler, the developer in read.md said that it uses the compiler "mingw-7.3.0", I tried to use the automatic installation provided in the installations of codeblocks, to manually install the compiler and declare the files in the toolchain but unfortunately I did not produce any results

compile it makefiles

Hello! I'm quite new to the world of C. I should compile a repository found on github but I can not configure the codeblocks compiler, the developer in read.md said that it uses the compiler "mingw-7.3.0", I tried to use the automatic installation provided in the installations of codeblocks, to manually install the compiler and declare the files in the toolchain but unfortunately I did not produce any results

usually with “make install”

compile it makefiles

but I guess you have to install gnu make on windows, there is a way to do so but I don’t remember how

sorry never used windows for years now

cmake is a useful tool to replace Makefile

but I guess you have to install gnu make on windows, there is a way to do so but I don’t remember how

WSL

wsl works

cmake is a useful tool to replace Makefile

yeah but it’s bloated and more complicated plus make files are almost in every repo but cmake files aren’t as popular

WSL

yeah wsl is a lot easier programming in c on windows is horrible

yeah but it’s bloated and more complicated plus make files are almost in every repo but cmake files aren’t as popular

disagree

tbh it is cross-platform so you can use it on machines other than Unix-like/based systems

disagree

it is really about preference some people even use ninija builds for some reason

it is really about preference some people even use ninija builds for some reason

Ninja is just generator. It can be used with cmake

Ninja is just generator. It can be used with cmake

I didn’t know that I use only make for my projects and cmake for repos that I try to compile from scratch

I didn’t know that I use only make for my projects and cmake for repos that I try to compile from scratch

cmake is very mature and defacto standard for c/cpp

while make force you use system depended utils

cmake is very mature and defacto standard for c/cpp

only if you using it on windows it is not a standard on GNU systems

only if you using it on windows it is not a standard on GNU systems

make is a GNU software

only if you using it on windows it is not a standard on GNU systems

cmake? it's cross-platform. you can use it everywhere. personally me compile the same project on windows/ubuntu/android. windows/STM32

you are right CMake is less especially when programming in C on Unix maybe because it is relatively new compared to Make which appeared in 1979

so when GNU guys made all their software built with make (because that was what they implemented back then)

legacy

so not a lot of their projects support cmake which is almost everything you might use on a modren linux machine today

Just use cmake for new projects)

I just check it out on wikipedia cmake actually generates makefiles on unix-like system

I just check it out on wikipedia cmake actually generates makefiles on unix-like system

You can configure it to do that, I think nowadays it generates ninja projects by default

You can configure it to do that, I think nowadays it generates ninja projects by default

yeah also that too

I just check it out on wikipedia cmake actually generates makefiles on unix-like system

Sure. Make by default. Or ninja. As well as on windows vcxproj for msvc or make and ninja

You can configure it to do that, I think nowadays it generates ninja projects by default

No. Ninja have some problems with mulicore building

No. Ninja have some problems with mulicore building

Maybe, but it's default at least as far as I can see

make is a GNU software

It doesnt matter

https://pastebin.com/prfzZs5u if anyone could please help explain why anytime i try to generate a random number through this Dice class, i get the same values (even though its been seeded).

https://pastebin.com/prfzZs5u if anyone could please help explain why anytime i try to generate a random number through this Dice class, i get the same values (even though its been seeded).

i created 2 objects from the class to generate random numbers but anytime i run the program they produce same numbers. I've tried to generate random numbers without the class and it works fine.

what online communities for the C language exist

cmake is very mature and defacto standard for c/cpp

Maybe he is suckless guy

Maybe he is suckless guy

cmake? nope

i created 2 objects from the class to generate random numbers but anytime i run the program they produce same numbers. I've tried to generate random numbers without the class and it works fine.

dont call srand here void Dice::rolldie(){ srand(time(0)); dieValue = rand() % 6 + 1; }

i created 2 objects from the class to generate random numbers but anytime i run the program they produce same numbers. I've tried to generate random numbers without the class and it works fine.

call dieValue = rand() % 6 + 1; in constructor for example BEFORE getDievalue call

what online communities for the C language exist

Almost only this one

call dieValue = rand() % 6 + 1; in constructor for example BEFORE getDievalue call

Okay thanks

BullShit С

cmake? nope

https://suckless.org/sucks/

https://suckless.org/sucks/

fun but much of topics just a hate

https://suckless.org/sucks/

why there are no python or js libs