Xcode: C++ program stops in the middle of the code

You have to declare the method, with just the signature, first in a place where it will be visible to the code calling it. Then you can define the method pretty much anywhere and the linker will connect it all together.

Also, I don't think you have any classes defined. A method is an action attached to a class. If there is no class, it is just a function.

Declare the function with:

void foo(void);

Define it with:

void foo(void)

{

std::cout << "I'm a foo!" << std::endl;

}

And call it with:

foo();

It seems that you have no other work to do. You are always participating in developer discussions. 🙂

Can I ask you a question? How many hours a day do you spend your time answering questions in threads?

And also, how many years has gone since the first time you participate in a discussion?

The problem is that when you call foo();, the compiler doesn't know it exists yet. You have to declare it with:

void foo(void);

Then, the compiler will know that is a function. When it sees that function being called, it will stick a placeholder for it. Then it will see a function and compile that to object code right next to the main() function. Finally, the linker will go through and connect all of those function placeholders into actual function calls.

No. I have lots more work to do. I just come here when I want to take a break from work. I probably spend 30 minutes a day answering questions here. I have been doing so since November, 2005.

Arc676 wrote:

You mentioned declaring a class. Does this affect the declaration of functions in any way? How does declaring a class in C++ affect the program?

The forums are being flaky today. I just figured out how to free up the works.

In C++, a class virtually identical to a struct. The only difference is that, in a struct, all members are public by default whereas they are private by default in a class. Internally, you can imagine that class/struct methods are just regular old functions whose first parameter is a pointer to the class/struct itself. Well, you don't have to imagine that because that is exactly how it works. There is also a little bit of vtable magic that redirects the function call to the appropriate derived class/struct.

Java just does two passes through the file so that function declarations aren't necessary. C++ compilers typically don't do that because C++ has traditionally been very difficult and time consuming to compile. Apple has fixed most of those speed problems in GCC with its Clang compiler. Consequently, in Objective-C you don't need to forward declare all methods as you do in C++.