what is wrong with the macro definition....

This is a discussion on what is wrong with the macro definition.... within the C Programming forums, part of the General Programming Boards category; Hi, I have following: Code: #define JPDM_NAME_SIZE 16 #define JPDM_DECLARE_BUFFER_DESCRIPTION(name, ptr, size) \ { \ JPDM_RECOVERY_STATE_NONE, \ name, \ (ptr), ...

  1. #1
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    what is wrong with the macro definition....

    Hi,

    I have following:

    Code:
    #define JPDM_NAME_SIZE 16
    
    #define JPDM_DECLARE_BUFFER_DESCRIPTION(name, ptr, size) \
        {                                           \
            JPDM_RECOVERY_STATE_NONE,               \
            name,                                   \
            (ptr),                                  \
            (size),                                 \
            NULL,                                   \
            0                                       \
        }
    
    typedef enum
    {
        JPDM_RECOVERY_STATE_NONE,
        JPDM_RECOVERY_STATE_NEW,
        JPDM_RECOVERY_STATE_RECOVERED,
        JPDM_RECOVERY_STATE_SAVED
    } teRecoveryState;
    
    
    //Following statement gives error
    JPDM_DECLARE_BUFFER_DESCRIPTION("Anoop",&sSwitch,sizeof(tsSwitch));
    Following macro definition gives me error:

    error: expected ';' before '}' token

    What is wrong in following statement?


    Thanks in advance

  2. #2
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    The backslash doesn't precede but follows the opening brace, as in
    Code:
    #define JPDM_DECLARE_BUFFER_DESCRIPTION(name, ptr, size) { \
        JPDM_RECOVERY_STATE_NONE,   \
        name,                       \
        (ptr),                      \
        (size),                     \
        NULL,                       \
        0;                          \
    }
    [Edit] And a semi-colon at the end as all statements are separated by commas.
    Last edited by itCbitC; 04-27-2010 at 08:48 AM. Reason: added semi-colon (in red)

  3. #3
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by itCbitC
    The backslash doesn't precede but follows the opening brace, as in
    That should not be a problem though, since the line with the opening brace has its own backslash.

    sanddune008, I suggest that you post the smallest and simplest program that demonstrates the error.
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  4. #4
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    Quote Originally Posted by laserlight View Post
    That should not be a problem though, since the line with the opening brace has its own backslash.
    Yep! good catch, and for some reason I totally missed that.
    It's the comma operator that needs a semi-colon terminator.

  5. #5
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    Don't know but could the problem be that you simply need to put the macro into context? eg:
    Code:
    #include <stdio.h>
    
    #define JPDM_NAME_SIZE 16
    
    #define JPDM_DECLARE_BUFFER_DESCRIPTION(name, ptr, size)\
           { \
             JPDM_RECOVERY_STATE_NONE, \
             name,                     \
             (ptr),                    \
             (size),                   \
             NULL,                     \
             0                         \
           }
    
    typedef enum
    {
        JPDM_RECOVERY_STATE_NONE,
        JPDM_RECOVERY_STATE_NEW,
        JPDM_RECOVERY_STATE_RECOVERED,
        JPDM_RECOVERY_STATE_SAVED
    } teRecoveryState;
    
    struct BuffS { int state1;     /* #### just guessing at this struct name and members... */
                   char * name;
                   void * p1;
                   size_t sz;
                   void*  p2;
                   int state2;
                  };
    
    int main(void)
    {
      int  sSwitch = 5;   /* ####  guessing at these vars too */
      char tsSwitch[] = "And the last to go will get to watch the others go before her... hahahaha";
    
      /* Following statement gives error  #### see how it now is a struct initializtion?  */
      struct BuffS bf1 = JPDM_DECLARE_BUFFER_DESCRIPTION("Anoop", &sSwitch, sizeof(tsSwitch));
    
      printf("bf1.state1=%d  name=%s  p1=%p  sz=%u  state2=%d  &sSwitch= %p \n",
              bf1.state1, bf1.name, bf1.p1, bf1.sz, bf1.state2, (void*)&sSwitch );
    
      return 0;
    }
    /*
    ~>  gcc -Wall -W -pedantic 100427_macro-00.c -o 100427_macro-00
    100427_macro-00.c: In function ‘main’:
    100427_macro-00.c:37: warning: initializer element is not computable at load time     #### refers to:  &sSwitch 
    100427_macro-00.c:37: warning: unused variable ‘bf1’
    ~>  
        #### no segfault at run
    ~>  ./100427_macro-00
    bf1.state1=0  name=Anoop  p1=0xbfeea0f4  sz=74  state2=0  &sSwitch= 0xbfeea0f4
    ~>  
        #### a look at the expanded macro:
    ~>  cc -E 100427_macro-00.c -o 100427_macro-00
    ~>  vi 100427_macro-00
    ...
    int main(void)
    {
      ...
      struct BuffS bf1 = { JPDM_RECOVERY_STATE_NONE, "Anoop", (&sSwitch), (sizeof(tsSwitch)), ((void *)0), 0 };
    
      return 0;
    }
    */
    I guess it works? Good exercise anyhow.
    Last edited by HowardL; 04-27-2010 at 11:11 AM.

  6. #6
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    Code:
    Following in header file
    
    #define JPDM_DECLARE_BUFFER_DESCRIPTION(name, ptr, size) \
        {                                           \
            JPDM_RECOVERY_STATE_NONE,               \
            name,                                   \
            (ptr),                                  \
            (size),                                 \
            NULL,                                   \
            0                                       \
        }
    
    
    typedef enum
    {
        JPDM_RECOVERY_STATE_NONE,
        JPDM_RECOVERY_STATE_NEW,
        JPDM_RECOVERY_STATE_RECOVERED,
        JPDM_RECOVERY_STATE_SAVED
    } teRecoveryState;
    
    typedef struct sJPDM_BufferDescription
    {
        teRecoveryState eState;
    
        char acName[JPDM_NAME_SIZE];
        void  *pvBuffer;
        uint32 u32BufferSize;
    
        struct sJPDM_BufferDescription *psNext;
        uint16 u16OffsetInFlash;
    
    } tsJPDM_BufferDescription;
    
    
    Following in source file
    
    typedef struct
    {
        teBindType eBound;
        uint64 sDestAddr;
        uint64 sParentAddr;
        bool_t bAppTimerStarted;
    }
    tsSwitch;
    
    
    //Application
    tsJPDM_BufferDescription sDescription;
    
    PUBLIC void vCbConfigureNetwork(void)
    {
    	sDescription = JPDM_DECLARE_BUFFER_DESCRIPTION("Anoop",&sSwitch,50);
    
    	// Set PAN_ID and other network stuff or defaults will be used
           Channel = 0x11;
    
    }

    error:

    /cygdrive/c/js/Application/LightSwitch/LightSwitch/Source/LightSwitch.c: In function 'vCbConfigureNetwork':
    /cygdrive/c/js/Application/LightSwitch/LightSwitch/Source/LightSwitch.c:148: error: expected expression before '{' token

  7. #7
    ATH0 quzah's Avatar
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    You can only make full on assignments at the time of declaration. You can't just do:
    Code:
    struct foo bar;
    
    bar = { a, b, c, d }; <-- you can't do that
    Quzah.
    Hope is the first step on the road to disappointment.

  8. #8
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    Thanks quzah......
    Thanks all for your time....

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