Circular Dependency error
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Thread: Circular Dependency error

  1. #1
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    Circular Dependency error

    Hi ,

    I was doing Uni assignment ( not looking for a full solution ) had to use the start up code provided ( other wise this issue would not have come ),
    when compiling the source I get the following error

    "pms_program.h:54:56: error: expected declaration specifiers or ‘...’ before ‘CourseType’"

    the code you are looking for in pms_course.h ( there is a circular dependency between pms.h , pms_course.h and pms_program.h)
    Head tutor provided a GUARD however don't think it works properly

    function prototype AppendProgram ( part of doubly linked list )



    I have attached the full course code.

    As much as I like I cannot change the structure of the startup code , I was hoping that someone know a solution or cam point me to the problem

    please see attached zip file for the entire source code.

    Thanks for Stopping by.
    Attached Files Attached Files

  2. #2
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    Re: Circular Dependency error

    I'm not too keen to uncompress that and look through all the possible files, so I'll just say this: sketch out the dependencies. What headers are included where? Do you define a class such that it requires the definition of another class that requires its definition?
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  3. #3
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    Re: Circular Dependency error

    Quote Originally Posted by aamir121a View Post
    Hi ,

    I was doing Uni assignment ( not looking for a full solution ) had to use the start up code provided ( other wise this issue would not have come ),
    when compiling the source I get the following error

    "pms_program.h:54:56: error: expected declaration specifiers or ‘...’ before ‘CourseType’"

    the code you are looking for in pms_course.h ( there is a circular dependency between pms.h , pms_course.h and pms_program.h)
    Head tutor provided a GUARD however don't think it works properly
    How is this supposed to work (from pms.h)?
    Code:
    /* program header files */
     #include "pms_program.h"
     #include "pms_course.h"
     #ifndef PMS_H
     #define PMS_H
    This is a non-starter right there.

    Secondly, there is no way to fix the problem of circular dependency unless you change the code.

    Regards,

    Paul McKenzie

  4. #4
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    Re: Circular Dependency error

    this is strictly a c code ( so no classes ) problem comes from the fact pms.h in included in pms_courses.h and pms_program.h and the are included in pms.h . ( hence the circular dependency )
    please also look at the typdef in pms.h
    Code:
    /* predeclare the program and course structs */
    typedef struct program* ProgramTypePtr;
    typedef struct course* CourseTypePtr;
    using them seems to solve the problem , however I do not understand why , perhaps an explanation will help me in the future.

  5. #5
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    Re: Circular Dependency error

    Quote Originally Posted by aamir121a
    this is strictly a c code ( so no classes )
    The same applies to structs.

    Quote Originally Posted by aamir121a
    using them seems to solve the problem , however I do not understand why
    It is probably because you are then not including the headers but using forward declarations instead.
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  6. #6
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    2kaud is online now Super Moderator Power Poster
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    Re: Circular Dependency error

    The .c file that doesn't compile is pms_course.c. To enable this to compile, the following change should be made

    Code:
    /*#include "pms_course.h"*/
    #include "pms.h"
    The other .c modules compile with only a couple of warnings.
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  7. #7
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    Re: Circular Dependency error

    Thank you all for posting

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