I have a header file and a cpp file. In the .h file I declared a class and a function with returning a reference:
.h file:
#include <iostream>
class testclass {
Car &createCar(int x, int y);
}
.cpp file:
#include<testclass.h>
Car testclass:&createCar(int x, int y)
{
....
}
But when I try to access the function in the .cpp file I get an error:
Declaration is not compatible
The function definition in .cpp file should be compatible with its decleration in .h file so modify it as follows.
.cpp file:
#include"testclass.h"
Car& testclass::createCar(int x, int y)
{
....
}
Note that I modified <testclass.h> to "testclass.h". use the brackets only with the built in headers.
Follow the following line if you want to know why you should use "testclass.h" instead of <testclass.h> and which one of them you should use Link
<> for any header whose path is relative to the project's header file search paths, which includes system headers. Use "" for any header whose path is relative to the source file currently being compiled.
#include are guidelines, all the standard states is that the locations of the headers is implementation defined. The actual guideline (in the standard) is to use <> for headers provided by the implementation, nothing to do with where they live in the filesystem (indeed, they don't even have to exist as real files). See C++20 [cpp.include].In your .h file, & is not a reference to a function. The & is part of the function's return type. So, the function actually returns a reference to a Car instance. It would help you to understand it if you actually write it that way:
Car& createCar(int x, int y);
As such, in the .cpp file, you need to move the & to the return type to match the declaration:
#include <iostream>
class testclass {
Car& createCar(int x, int y);
};
#include "testclass.h"
Car& testclass::createCar(int x, int y)
{
....
}
CarClass &in the header andCarin the .cpp file&#include <testclass.h>implies that your header is in the system include path. If you want to search the current directory, use#include "testclass.h"