extern char* problem

[alistair3408]

Hi, I'm quite new to C. I have 4 .h files and one header file.

header.h

//variables
extern char CWD[PATH_MAX];

fileio.c

char CWD[PATH_MAX];
strcpy(CWD,temp);

haar.c

strcpy(imagePath, CWD);

I'm getting the error:

haar.c:62: undefined reference to `CWD'

I've looked around the net quite a bit about extern variables and this seems to be the right thing to do - declare extern in header (which is included in every .c file) and then initialise it once (in fileio.c) and use it anywhere (in haar.c).

Why am i still getting this error?

[tabstop]

You have to declare it in file scope in fileio.c. Given that immediately underneath it is "strcpy(CWD,temp)", that indicates to me that your CWD lives inside a function, and extern can't help you there.

[itCbitC]

You need an extern declaration for CWD in haar.c, outside of any function.