Problems with sizeof function

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  • =?Utf-8?B?RnJhbg==?=
    #1

    Problems with sizeof function

    sHi!

    I have a very strange problem with the behaviour of the sizeof command. I
    have tested it in vc6,vc 2001 and vc 2003. The problem is quite simple.

    When I made a sizeof to the next struct, it returns that the size is 40
    instead of 38. I consider that a short is 2 bytes, float 4 bytes, unsigned
    long 4 byte, unsigned short 2 bytes. If i add all the size of the fields it
    must be 38 but sizeof says that is 40.

    The struct is the next:

    typedef struct
    {
    short est;
    short numbe1;
    float dst;
    float Line;
    unsigned long tmp;
    float tmp1;
    float tmp2;
    unsigned long tck;
    unsigned long tl;
    unsigned short dp;
    unsigned short ldact;
    unsigned short lnc;
    }test;

    If I remove one unsigned short field, the size change to 36, but if made
    size of (unsigned short) it return 2.

    This is the other "crazy" struct:

    typedef struct
    {
    short est;
    short numbe1;
    float dst;
    float Line;
    unsigned long tmp;
    float tmp1;
    float tmp2;
    unsigned long tck;
    unsigned long tl;
    unsigned short dp;
    unsigned short ldact;
    }test;

    I'm getting crazy, any idea??


    Thank you very much for your help.



    The structure is the next:


    Tags: None
    • Cholo Lennon
      #2
      Re: Problems with sizeof function

      This is a common question. Take a look to:

      429
      http://groups.google.com/group/microsoft.public.vc.language/browse_frm/thread/8e7400441b97eb1e/72c336cb677db72c?lnk=gst&q=struct+s

      izeof#72c336cb6 77db72c

      Regards

      --
      Cholo Lennon
      Bs.As.
      ARG


      "Fran" <Fran@discussio ns.microsoft.co mwrote in message news:193B0BFA-3231-43CE-9DB6-3ABC9D589CB3@mi crosoft.com...
      sHi!
      >
      I have a very strange problem with the behaviour of the sizeof command. I
      have tested it in vc6,vc 2001 and vc 2003. The problem is quite simple.
      >
      When I made a sizeof to the next struct, it returns that the size is 40
      instead of 38. I consider that a short is 2 bytes, float 4 bytes, unsigned
      long 4 byte, unsigned short 2 bytes. If i add all the size of the fields it
      must be 38 but sizeof says that is 40.
      >
      The struct is the next:
      >
      typedef struct
      {
      short est;
      short numbe1;
      float dst;
      float Line;
      unsigned long tmp;
      float tmp1;
      float tmp2;
      unsigned long tck;
      unsigned long tl;
      unsigned short dp;
      unsigned short ldact;
      unsigned short lnc;
      }test;
      >
      If I remove one unsigned short field, the size change to 36, but if made
      size of (unsigned short) it return 2.
      >
      This is the other "crazy" struct:
      >
      typedef struct
      {
      short est;
      short numbe1;
      float dst;
      float Line;
      unsigned long tmp;
      float tmp1;
      float tmp2;
      unsigned long tck;
      unsigned long tl;
      unsigned short dp;
      unsigned short ldact;
      }test;
      >
      I'm getting crazy, any idea??
      >
      >
      Thank you very much for your help.
      >
      >
      >
      The structure is the next:
      >
      >



        Comment

        • Mark Salsbery [MVP]
          #3
          Re: Problems with sizeof function

          You may want to read the "Remarks" section here as well:

          http://msdn2.microsoft.com/en-us/lib...65(VS.80).aspx

          Mark

          --
          Mark Salsbery
          Microsoft MVP - Visual C++


          "Fran" <Fran@discussio ns.microsoft.co mwrote in message
          news:193B0BFA-3231-43CE-9DB6-3ABC9D589CB3@mi crosoft.com...
          sHi!
          >
          I have a very strange problem with the behaviour of the sizeof command. I
          have tested it in vc6,vc 2001 and vc 2003. The problem is quite simple.
          >
          When I made a sizeof to the next struct, it returns that the size is 40
          instead of 38. I consider that a short is 2 bytes, float 4 bytes, unsigned
          long 4 byte, unsigned short 2 bytes. If i add all the size of the fields
          it
          must be 38 but sizeof says that is 40.
          >
          The struct is the next:
          >
          typedef struct
          {
          short est;
          short numbe1;
          float dst;
          float Line;
          unsigned long tmp;
          float tmp1;
          float tmp2;
          unsigned long tck;
          unsigned long tl;
          unsigned short dp;
          unsigned short ldact;
          unsigned short lnc;
          }test;
          >
          If I remove one unsigned short field, the size change to 36, but if made
          size of (unsigned short) it return 2.
          >
          This is the other "crazy" struct:
          >
          typedef struct
          {
          short est;
          short numbe1;
          float dst;
          float Line;
          unsigned long tmp;
          float tmp1;
          float tmp2;
          unsigned long tck;
          unsigned long tl;
          unsigned short dp;
          unsigned short ldact;
          }test;
          >
          I'm getting crazy, any idea??
          >
          >
          Thank you very much for your help.
          >
          >
          >
          The structure is the next:
          >
          >

            Comment

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