What is this difference in C++?

Question

I've been wondering, is there a difference between the following code, and if so, what is the difference?

class Example {
public:
void greet() {
cout << "Hello." << endl;
}
};

AND

class Example {
public:
void greet();
};

void Example::greet() {
cout << "Hello." << endl;
}

Answer 1

So if I had a like "base.h" that included the Example class above:

class Example {
public:
void greet();
};

And another file called, say, base.cpp that was:

#include "base.h"

using namespace std;

void Example::greet() {
cout << "Hello" << endl;
}

That is how it would work?

Answer 2

These two effectively do the same thing, but the second one defines the function outside of the class. You may do this if you want a header file (.h) with just the class members and function prototypes separate from the source file (.cpp) with the function definitions. Notice how you need to use the scope resolution (::) operator in the second example in order to say that you are defining the function that is in the class Example.

Answer 3

@「ＨＡＰＰＹ ＴＯ ＨＥＬＰ」

So how exactly do .h files work? Is that where you use #include?

As in, in the .cpp files do you use #include the .h files

Answer 4

Why is that an error? Sorry for so many questions just learning

Answer 5

Oh yeah I was just assuming that iostream was included, but okay. Like the class suggests, just an example :P