Thread: how to declare an external variable of type "enum"?

The definition of the enum type must be visible when compiling (and remember: source code files are compiled independently of one another). This is the job header files were born to do. You can put the enum definition and the extern in the header, and any source code that needs to know about it #includes the header.

Originally Posted by tabstop

The definition of the enum type must be visible when compiling (and remember: source code files are compiled independently of one another). This is the job header files were born to do. You can put the enum definition and the extern in the header, and any source code that needs to know about it #includes the header.

: O That is the correct answer, two points for tabstop. I will simply place in header.h the code that is currently in main.c

Code:

enum whoseturn {B, W};
enum whoseturn color=W;

Oh, no, that isn't working quite right after all. I added it to the header, but now I'm getting this error:

Code:

input.o(.data+0x0): multiple definition of `color'
main.o(.data+0x0): first defined here
convertfen.o(.data+0x0): multiple definition of `color'
main.o(.data+0x0): first defined here

I don't define it in main anymore, so it seems to be defining it everytime the header is accessed?

This is in my header file:

Code:

enum whoseturn color {B, W};

This is in my main.c:

Code:

color=W;

This is my error:

Code:

main.c: In function `main':
main.c:62: `color' undeclared (first use in this function)
main.c:62: `W' undeclared (first use in this function)

And this is what I need in my header:

Code:

enum whoseturn {B, W};
enum whoseturn color;

Thanks everyone!

Originally Posted by Adam Rinkleff

And this is what I need in my header:

Code:

enum whoseturn {B, W};
enum whoseturn color;

Thanks everyone!

No that most definitely isn't what you need in your header. You need the definition of the whoseturn, and an extern variable declaration. Right now you have two separate color variables, one in your main, and one in your other file.

Originally Posted by King Mir

You don't need a global variable for something like this.

I do because I don't really know what I'm doing, so I'm happy if it compiles, and passing variables back and forth seems awfully difficulty.

: DDDDDDd

Originally Posted by laserlight

Working with global variables is even more difficult because you have to keep global state in your mind all the time. When you don't really know what you're doing, global variables => guaranteed epic fail.

Can you explain, because I really don't understand. I don't really have a global state to keep track of, I think you are overestimating the amount of skill that I possess. I'm just trying to write a chess program (I'm a chess player, not a programmer), and I find that just about every function I make wants to know the color, along with about 50'000 other variables, so I've just made everything global.

Originally Posted by Adam Rinkleff

...I think you are overestimating the amount of skill that I possess. I'm just trying to write a chess program (I'm a chess player, not a programmer), ...

You do realize that creating a chess program is one of the more difficult programming tasks to perform right?

Originally Posted by AndrewHunter

You do realize that creating a chess program is one of the more difficult programming tasks to perform right?

Not true, creating a good chess program might be very hard; but the bad ones was not so hard.

Tim S.