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From:	CBFalconer <cbfalconer AT yahoo DOT com>
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Structure size problem
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Date:	Fri, 15 Feb 2002 07:53:24 GMT
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Alvin Lau wrote:
> 
> Here is my program:
> 
> #include <stdio.h>
> 
> typedef unsigned char byte;
> typedef unsigned long dword;
> 
> struct tagKFName2 {
>   dword Index;
>   byte KFType;
>   char KFName[30];
> };
> struct tagKFName {
>   byte unknown[5];
>   char KFName[30];
> };
> typedef struct tagKFName KFNAME;
> typedef struct tagKFName2 KFNAME2;
> int main()
> {
>   KFNAME buf;
>   KFNAME2 buf2;
> 
>   printf("Size KFNAME: %d\n\nSize KFNAME2:
> %d\n",sizeof(KFNAME),sizeof(KFNAME2));
>   printf("Index: %d\nKFType: %d\nKFName:
> %d\n",sizeof(buf2.Index),sizeof(buf2.KFType),sizeof(buf2.KFName));
> 
>   return 0;
> }
> 
> After running this program, I got the output as follow:
> 
> Size KFNAME: 35
> 
> Size KFNAME2: 36
> Index: 4
> KFType: 1
> KFName: 30
> 
> Obviously there have a problem about the structure size in KFNAME2, this
> structure has three members (Index,KFType,KFName). According the output of
> this program, the size of Index is 4, KFType is 1, KFName is 30. Then 4+1+30
> should be 35, but the total size of KFNAME2 is 36. So, I want to ask some
> questions:
> Is this a bug in DJGPP ?
> How to solve this problem ?

This is a FAQ.  Hunt down the C faq.  gcc is absolutely right.
-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT XXXXworldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   (Remove "XXXX" from reply address. yahoo works unmodified)
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