. <- Have you included this file in the list of files to be compiled by compiler A common mistake most beginners make with C/C++ compilation is that they assume that when a CPP file includes a header file say a.h then the corresponding implementation file i.e. a.cpp is automatically compiled. This is not the case. If you have multiple CPP files, you have to specifically request the compiler to compile all of them

No i have not done it

. <- Have you included this file in the list of files to be compiled by compiler A common mistake most beginners make with C/C++ compilation is that they assume that when a CPP file includes a header file say a.h then the corresponding implementation file i.e. a.cpp is automatically compiled. This is not the case. If you have multiple CPP files, you have to specifically request the compiler to compile all of them

I was using g++ to compile it because gcc gives me an error

. <- Have you included this file in the list of files to be compiled by compiler A common mistake most beginners make with C/C++ compilation is that they assume that when a CPP file includes a header file say a.h then the corresponding implementation file i.e. a.cpp is automatically compiled. This is not the case. If you have multiple CPP files, you have to specifically request the compiler to compile all of them

How can i make a list of files to compile without adding every file to the arguments?

How can i make a list of files to compile without adding every file to the arguments?

Use a build tool like make, cmake, meson, bazel2 etc etc ..

what? msvc has good support for header units

Read my message carefully before replying. I said MS added support for header units later. So if he was using a version prior to the one where the support was added, it is possible that he could be facing issues with header units

I was using g++ to compile it because gcc gives me an error

Know the difference between GCC and g++ before blindly switching between their usage.

Read my message carefully before replying. I said MS added support for header units later. So if he was using a version prior to the one where the support was added, it is possible that he could be facing issues with header units

later than what? i use header units at least 2 years

later than what? i use header units at least 2 years

Later than when they started supporting standard library imports as modules using import std.core;

Later than when they started supporting standard library imports as modules using import std.core;

you're kidding?

msvc provided experimental std modules before modules was standardized in C++20 import std; added only in C++23

msvc provided experimental std modules before modules was standardized in C++20 import std; added only in C++23

between that points of time, msvc started support header units

you're kidding?

No I am not. MS went out of their way to support standard library imports before header units because this is what they anticipated would be the most troublesome change. This is why MS is far ahead of GCC and Clang. Supporting header units is a minor change after supporting scanning dependencies, inclusions and build order definitions. So MS made this change much faster while GCC and Clang went ahead with supporting header units and module partitions first and their support for the C++23 requirement of allowing imports of standard library components as modules instead of header units is still wanting.

msvc provided experimental std modules before modules was standardized in C++20 import std; added only in C++23

Microsoft supported import core; much earlier which is what has been changed to import std; now

Microsoft supported import core; much earlier which is what has been changed to import std; now

std.core and others was experimental modules, before standard modules, and they are osbsolete

std.core and others was experimental modules, before standard modules, and they are osbsolete

I know. Why are you making irrelevant points? My point was that MS supported std.core before header units. Now are u disagreeing with that?

I know. Why are you making irrelevant points? My point was that MS supported std.core before header units. Now are u disagreeing with that?

what ever, in the std.core time header units did not exists, because microsoft planned to drop macros at all you trying to compare different standards and technologies

why you didn't compare clang modules with header units? clang modules exists since forever

what ever, in the std.core time header units did not exists, because microsoft planned to drop macros at all you trying to compare different standards and technologies

No. Do you even understand what went behind the support for std.core? Microsoft made changes to support scanning dependencies, build order manifest generation and inclusion file order checks. All of this made them well placed to support the C++23 requirement of supporting import std; Once all these changes were made supporting header unit generation from header files was a minor change. I was merely suggesting that he could be using the version of Visual Studio which had support for std.core but not for header units. I wasn't saying that is the problem. I was suggesting that could be the case. From the information he gave, all we can do is infer why it could have failed.

why you didn't compare clang modules with header units? clang modules exists since forever

Clang modules is a feature that is different from the std.core feature in Visual Studio. Clang added this feature to move away from precompiled headers. This was very different from the modules feature added in C++20. Moreover his question was related to Visual studio. So I don't quite understand why I should make this comparison.

Clang modules is a feature that is different from the std.core feature in Visual Studio. Clang added this feature to move away from precompiled headers. This was very different from the modules feature added in C++20. Moreover his question was related to Visual studio. So I don't quite understand why I should make this comparison.

and std.core is different from std

and std.core is different from std

Can you even read? When did I say they are the same? I said the changes required for supporting std.core is what made MS support import std; easily. If you are not sure read what MS did to support this feature, read more about it. std.core is much more closer to modules in C++20 than clang's module feature was

Hi guys.

Can someone please help me with my code?

I have debug assertion failed error with a wizard generated code

Cuz i get warning can somebody tell me what is markdown formatting

Thx

I have never worked with Java and I am not familiar with this language But I want to know if it is true that they are very similar in oop discussion?

Know the difference between GCC and g++ before blindly switching between their usage.

what is the difference

i thought they were both c compilers

i have tried using g++ *.cpp but it still doesnt work

it tells me undefined reference to `File::OpenFile(char const*)

this is the full source

https://pastebin.com/4db0AvRc

help

Hello I have a problem that the c++ does not show me where it is wrong as usual. Can someone tell me what to do?

i have tried using g++ *.cpp but it still doesnt work

i guess you need to compile like this g++ -o main src/File.cpp main.cpp cmiiw

i guess you need to compile like this g++ -o main src/File.cpp main.cpp cmiiw

yes i have done it

but now i get a new error

main.o:main.cpp:(.rdata$.refptr._ZTV4File[.refptr._ZTV4File]+0x0): undefined reference to `vtable for File'

i have also included fstream in the File class

main.o:main.cpp:(.rdata$.refptr._ZTV4File[.refptr._ZTV4File]+0x0): undefined reference to `vtable for File'

try this g++ -o main -I src/ src/File.cpp main.cpp

Hello I have a problem that the c++ does not show me where it is wrong as usual. Can someone tell me what to do?

.

Hello I have a problem that the c++ does not show me where it is wrong as usual. Can someone tell me what to do?

perhaps your syntax is ok but your logic is not? try compile simple error syntax like main.cpp func main() { fmt.Println("!... Hello World ...!") } hehe

try this g++ -o main -I src/ src/File.cpp main.cpp

now i get two errors: C:\Users\*\AppData\Local\Temp\ccGWovYT.o:main.cpp:(.rdata$.refptr._ZTV6STFile[.refptr._ZTV6STFile]+0x0): undefined reference to `vtable for STFile' and C:\Users\*\AppData\Local\Temp\ccGWovYT.o:main.cpp:(.rdata$.refptr._ZTV6STFile[.refptr._ZTV6STFile]+0x0): undefined reference to `vtable for File'

perhaps your syntax is ok but your logic is not? try compile simple error syntax like main.cpp func main() { fmt.Println("!... Hello World ...!") } hehe

Ok

perhaps your syntax is ok but your logic is not? try compile simple error syntax like main.cpp func main() { fmt.Println("!... Hello World ...!") } hehe

thinks

https://pastebin.com/4db0AvRc

g++ -o output File.cpp STFile.cpp main.cpp Add include guards for your header files as well.

g++ -o output File.cpp STFile.cpp main.cpp Add include guards for your header files as well.

what are include guards for

what are include guards for

https://www.geeksforgeeks.org/include-guards-in-c/

now i get two errors: C:\Users\*\AppData\Local\Temp\ccGWovYT.o:main.cpp:(.rdata$.refptr._ZTV6STFile[.refptr._ZTV6STFile]+0x0): undefined reference to `vtable for STFile' and C:\Users\*\AppData\Local\Temp\ccGWovYT.o:main.cpp:(.rdata$.refptr._ZTV6STFile[.refptr._ZTV6STFile]+0x0): undefined reference to `vtable for File'

File.hpp change this virtual void ProcessFile(); -> virtual void ProcessFile(){}; main.cpp add this void STFile::ProcessFile() {} cmiiw

File.hpp change this virtual void ProcessFile(); -> virtual void ProcessFile(){}; main.cpp add this void STFile::ProcessFile() {} cmiiw

but i dont want to implement ProcessFile in main.cpp, i want it to be in STFile.cpp

but i dont want to implement ProcessFile in main.cpp, i want it to be in STFile.cpp

g++ -o output File.cpp STFile.cpp main.cpp

g++ -o output File.cpp STFile.cpp main.cpp

C:\Users\*\AppData\Local\Temp\ccpxt4Mi.o:File.cpp:(.rdata$.refptr._ZTV4File[.refptr._ZTV4File]+0x0): undefined reference to `vtable for File'

C:\Users\*\AppData\Local\Temp\ccpxt4Mi.o:File.cpp:(.rdata$.refptr._ZTV4File[.refptr._ZTV4File]+0x0): undefined reference to `vtable for File'

File.hpp change this virtual void ProcessFile(); -> virtual void ProcessFile(){};

File.hpp change this virtual void ProcessFile(); -> virtual void ProcessFile(){};

#ifndef FILE_H #define FILE_H #include <fstream> class File { public: std::ifstream file; int OpenFile(const char *fname) {}; virtual void ProcessFile() {}; }; #endif // FILE_H

File.hpp change this virtual void ProcessFile(); -> virtual void ProcessFile(){};

i have done this but it still tells that error

error: redefinition of 'int File::OpenFile(const char*)' 4 | int File::OpenFile(const char *fname) {

https://pastebin.com/UxU9kCxp

error: redefinition of 'int File::OpenFile(const char*)' 4 | int File::OpenFile(const char *fname) {

it show now error here

https://pastebin.com/UxU9kCxp

what do you edited here

it show now error here

the code you sent me shows that error?

what do you edited here

try it first

try it first

yes i need to know what to copy

yes i need to know what to copy

copy all of them does it still show error? project/ main.cpp src/ File.hpp File.cpp STPFile.hpp STPFile.cpp g++ -I src/ src/File.cpp src/STFile.cpp main.cpp

copy all of them does it still show error? project/ main.cpp src/ File.hpp File.cpp STPFile.hpp STPFile.cpp g++ -I src/ src/File.cpp src/STFile.cpp main.cpp

with that command the error is gone

copy all of them does it still show error? project/ main.cpp src/ File.hpp File.cpp STPFile.hpp STPFile.cpp g++ -I src/ src/File.cpp src/STFile.cpp main.cpp

what did you edited? and what that command does?

what did you edited? and what that command does?

File.hpp: #include <fstream> class File { public: std::ifstream file; int OpenFile(const char *fname); virtual void ProcessFile(){}; <- this }; g++ -I ( I == also search this dir for library )

File.hpp: #include <fstream> class File { public: std::ifstream file; int OpenFile(const char *fname); virtual void ProcessFile(){}; <- this }; g++ -I ( I == also search this dir for library )

i understand

File.hpp: #include <fstream> class File { public: std::ifstream file; int OpenFile(const char *fname); virtual void ProcessFile(){}; <- this }; g++ -I ( I == also search this dir for library )

but why you do that

why you add the {}

why you add the {}

as far as i know virtual class function member must have body function and {} == empty body

as far as i know virtual class function member must have body function and {} == empty body

so virtual function must always have an empty body?

so virtual function must always have an empty body?

not always is up to you. this is some example https://www.geeksforgeeks.org/virtual-function-cpp/

Guys when you use ineheritance with std::vector<T> Does it inerehit also constructors?

Guys when you use ineheritance with std::vector<T> Does it inerehit also constructors?

Don't inherit from std::vector or any std types for that matter unless the type is specifically advertised for being inherited from (std::enable_shared_from_this). There is even a C++ guideline for this. You can search for it.

Hie can u convert kilometres to meters?

In .c

so virtual function must always have an empty body?

Unless it is a pure virtual function in which case it is ok for it to not have a body.

Hie can u convert kilometres to meters?

No homework help here

Don't inherit from std::vector or any std types for that matter unless the type is specifically advertised for being inherited from (std::enable_shared_from_this). There is even a C++ guideline for this. You can search for it.

Can u get me a link?