Using header and its implementation in an another class?

Asked Apr 17 '18 at 20:16

Active Apr 17 '18 at 20:17

Viewed 32 times

How can I use a header file and it's implementation?

A.h

class ClassA { 
int value;
ClassA();
}

ClassA.cpp

#include "A.h"
ClassA(){
this->value = 0;
}

ClassB.cpp

#include "A.h"
ClassB(){
this->value = 1;
}
int main(){
//I want to create an Object of ClassA.
ClassA ca = new ClassA(); //but this is not working
}

Hi, I have two headers and two source files.

I want to create an object of ClassA in ClassB. How is this possible? I get always the following error:

Undefined symbols for architecture x86_64: "ClassA::ClassA()", referenced from: _main in ClassB-9b2a5e.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Where is my mistake?

edited Apr 17 '18 at 20:17

Fred Larson

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asked Apr 17 '18 at 20:16

Joe Max

Where's the header for `ClassB`? – R Sahu Apr 17 '18 at 20:18
`ClassA::ClassA() { ... }` should be your ClassA.cpp. Also `new ClassA()` returns `ClassA*` (note: pointer) – Matthew Woo Apr 17 '18 at 20:29
Its still not working! :/ – Joe Max Apr 17 '18 at 20:36
Off-topic: You don't need to use the `this->` syntax. Only use it when you can't name your method parameters differently than the data members. – Thomas Matthews Apr 17 '18 at 20:42
You don't need to use `new` to create objects or instances of a class. C++ != Java, C++ != C#. – Thomas Matthews Apr 17 '18 at 20:43
If I do this: ClassA a1; I get the same error. :/ – Joe Max Apr 17 '18 at 20:48

Using header and its implementation in an another class?

0 Answers0