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Initialize object from .cpp file

Quick question, can I initialize an object (found uninitialized inside .h file) from inside a method inside a .cpp file? I tried with "obj = Object ();" but it doesn't work from within the method, it only works if I put it inside the file.h EX: file.h Object obj; EX: file.cpp void XXXX::myFun(int param) { obj = Object(param) }

2nd Dec 2021, 9:19 PM
Mick
Mick - avatar
44 Respostas
+ 2
So you're also programming Arduino, I understand now why you didn't care to know it ūüėÖ I think I found a solution which is replacing OtherClass a; by OtherClass* a; Then, replacing a = OtherClass(0); by a = new OtherClass(0); With this, all works fine but don't forget to apply the same corections for b
3rd Dec 2021, 3:04 PM
VCoder
VCoder - avatar
+ 1
Listen, I developed once a library for arduino (deleted now) and I had this problem and beside the new operator I've found two solutions : 1_Inspired from Kotlin : replace the OtherClass constructor by OtherClass::OtherClass() {}, then make : OtherClass::init(int param) {}, next : OtherClass a; and finally in the begin() method replace a = OtherClass(0) by a.init(0) (do the same for b) 2_Initialize a and b with a defult value when declaration (ex: OtherClass a = OtherClass(1)) then do what you want in the begin() method After one of these solutions, c.a.fun() will work
3rd Dec 2021, 4:03 PM
VCoder
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0
Try to use instead : Object obj() or Object obj = new Object()
3rd Dec 2021, 11:34 AM
VCoder
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0
Wrong and wrong
3rd Dec 2021, 12:05 PM
Mick
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0
One minute, please reformulate your question, you want to program a module or execute a simple code ?
3rd Dec 2021, 12:10 PM
VCoder
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0
I'm building a library, in the header file there are two uninitialized objects, in the cpp file I use a "begin()" method to initialize the two objects in the header file, only it's not as simple as I thought since I just write: a = Object(param); it gives me an error
3rd Dec 2021, 12:17 PM
Mick
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0
the problem is just that. If I write Object a = Object(param); inside the header file, the code compiles perfectly.
3rd Dec 2021, 12:20 PM
Mick
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0
Listen, I will make a tutorial about module programming in C++ because I did it too but without the files, I can't understand your code, but you may check this article which will help you : https://www.arduino.cc/en/Hacking/libraryTutorial It's a C++ library making tutorial for Arduino, if you find these functions : digitalWrite, delay and pinMode, just understand that they are simple functions, but if you follow me, I'll be able to explain what are these functions and what is Arduino
3rd Dec 2021, 12:35 PM
VCoder
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0
I don't care what is arduino, I care if and how an obj can be initialized from within a method in cpp file
3rd Dec 2021, 12:38 PM
Mick
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0
Please, give me the files
3rd Dec 2021, 12:39 PM
VCoder
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And from where Object comes ?
3rd Dec 2021, 12:39 PM
VCoder
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I don't understand, do I have to use a pointer? Should I use ClassName::Obj? What can I do ?
3rd Dec 2021, 12:44 PM
Mick
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0
//XXXX.h #ifndef XXXX_h #define XXXX_h #include "Object.h" Object obj; void myFun(int); #endif //XXXX.cpp #include "Object.h" #include "XXXX.h" void myFun(int param) { obj = Object(param); } //main.cpp #include <iostream.h> #include "XXXX.h" int main() { begin(5); return 0; } I think this is what you want
3rd Dec 2021, 1:25 PM
VCoder
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0
//Class.h# #ifndef CLASS_H #define CLASS_H #include "OtherClass.h" class Class { public: Class(); void begin(); OtherClass a; OtherClass b; }; #endif //Class.cpp# #include "Class.h" Class::Class() { } void Class::begin() { a = OtherClass(0); b = OtherClass(0); } //OtherClass.h# #ifndef OTHER_CLASS_H #define OTHER_CLASS_H class OtherClass { public: OtherClass(int param); }; #endif //OtherClass.cpp# #include "OtherClass.h" OtherClass::OtherClass(int param) { }
3rd Dec 2021, 1:40 PM
Mick
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0
This is code
3rd Dec 2021, 1:40 PM
Mick
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0
Thank you but your code is correct, so what's the problem or the error ?
3rd Dec 2021, 1:55 PM
VCoder
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0
not compile
3rd Dec 2021, 1:56 PM
Mick
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0
What's the error message ?
3rd Dec 2021, 1:56 PM
VCoder
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0
C:\Users\Mick\Documents\Arduino\libraries\Class\Class.cpp: In constructor 'Class::Class()': C:\Users\Mick\Documents\Arduino\libraries\Class\Class.cpp:4:14: error: no matching function for call to 'OtherClass::OtherClass()' Class::Class() { ^ In file included from C:\Users\Mick\Documents\Arduino\libraries\Class\Class.h:4:0, from C:\Users\Mick\Documents\Arduino\libraries\Class\Class.cpp:1: C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:8:5: note: candidate: OtherClass::OtherClass(int) OtherClass(int param); ^~~~~~~~~~ C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:8:5: note: candidate expects 1 argument, 0 provided C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate: constexpr OtherClass::OtherClass(const OtherClass&) class OtherClass { ^~~~~~~~~~ C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate expects 1 argument, 0 provided C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate: constexpr OtherClass::OtherClass(OtherClass&&) C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate expects 1 argument, 0 provided C:\Users\Mick\Documents\Arduino\libraries\Class\Class.cpp:4:14: error: no matching function for call to 'OtherClass::OtherClass()' Class::Class() { ^ In file included from C:\Users\Mick\Documents\Arduino\libraries\Class\Class.h:4:0, from C:\Users\Mick\Documents\Arduino\libraries\Class\Class.cpp:1: C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:8:5: note: candidate: OtherClass::OtherClass(int) OtherClass(int param); ^~~~~~~~~~ C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:8:5: note: candidate expects 1 argument, 0 provided C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate: constexpr OtherClass::OtherClass(const OtherClass&) class OtherClass { ^~~~~~~~~~ C:\Users\Mick\Docume
3rd Dec 2021, 2:11 PM
Mick
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nts\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate expects 1 argument, 0 provided C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate: constexpr OtherClass::OtherClass(OtherClass&&) C:\Users\Mick\Documents\Arduino\libraries\Class\OtherClass.h:5:7: note: candidate expects 1 argument, 0 provided
3rd Dec 2021, 2:12 PM
Mick
Mick - avatar