I am trying to compile 2 classes in C++ with the following command:
g++ Cat.cpp Cat_main.cpp -o Cat
But I receive the following error:
Cat.cpp:10:10: error: variable ‘Cat Joey’ has initializer but incomplete type
Could someone explain to me what this means? What my files basically do is create a class (Cat.cpp
) and create an instance (Cat_main.cpp
). Here is my source code:
Cat.cpp:
#include <iostream>
#include <string>
class Cat;
using namespace std;
int main()
{
Cat Joey("Joey");
Joey.Meow();
return 0;
}
Cat_main.cpp:
#include <iostream>
#include <string>
using namespace std;
class Cat
{
public:
Cat(string str);
// Variables
string name;
// Functions
void Meow();
};
Cat::Cat(string str)
{
this->name = str;
}
void Cat::Meow()
{
cout << "Meow!" << endl;
return;
}
This question is related to
c++
class
compiler-construction
I got a similar error and hit this page while searching the solution.
With Qt this error can happen if you forget to add the QT_WRAP_CPP( ... )
step in your build to run meta object compiler (moc). Including the Qt header is not sufficient.
It's not related to Ken's case directly, but such an error also can occur if you copied .h file and forgot to change #ifndef
directive. In this case compiler will just skip definition of the class thinking that it's a duplication.
Sometimes, the same error occurs when you forget to include the corresponding header
.
You cannot define a variable of an incomplete type. You need to bring the whole definition of Cat
into scope before you can create the local variable in main
. I recommend that you move the definition of the type Cat
to a header and include it from the translation unit that has main
.
Source: Stackoverflow.com