extern char* problem

This is a discussion on extern char* problem within the C Programming forums, part of the General Programming Boards category; Hi, I'm quite new to C. I have 4 .h files and one header file. header.h Code: //variables extern char ...

  1. #1
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    extern char* problem

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

    header.h
    Code:
    //variables
    extern char CWD[PATH_MAX];
    fileio.c
    Code:
    char CWD[PATH_MAX];
    strcpy(CWD,temp);

    haar.c
    Code:
    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?

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    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.

  3. #3
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    You need an extern declaration for CWD in haar.c, outside of any function.

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