From: vbresan AT jagor DOT srce DOT hr (Viktor Bresan)
Newsgroups: comp.os.msdos.djgpp
Subject: Probably newbie question (fread)
Date: 12 Oct 1999 14:35:10 +0200
Organization: Sveucilisni Racunarski CEntar
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Message-ID: <pm3A4UJ05kJa092yn@jagor.srce.hr>
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

I have a problem with the following code.
fread (in which I read in complete struct) doesn't act as I expect.
If I comment that line, and uncomment all other lines with fread
(that means if i read in struct fields one by one) i get expected result.
You can test the program on any bmp file.
The same code compiled with BC++ 3.1 acts normal in both cases.

What causes two different behaviors in this program?
Should I avoid filling complete structs with one fread?
Thanx.


---------------------------------- begin --------------------------------------
#include <stdio.h>


struct BITMAPFILEHEADER
 { unsigned short bfType;
   unsigned long  bfSize;
   unsigned short bfReserved1;
   unsigned short bfReserved2;
   unsigned long  bfOffBits;
 };


int main(int argc, char *argv[])
 {
   printf("\n\n");

   if(argc == 2 )
     { FILE *pFILE;

       pFILE = fopen(argv[1],"rb");
       if(pFILE)
         { BITMAPFILEHEADER bmfh;

/* here */ fread(&bmfh,sizeof(BITMAPFILEHEADER),1,pFILE);

/* & here  fread(&bmfh.bfType,sizeof(unsigned short),1,pFILE);
           fread(&bmfh.bfSize,sizeof(unsigned long),1,pFILE);
           fread(&bmfh.bfReserved1,sizeof(unsigned short),1,pFILE);
           fread(&bmfh.bfReserved2,sizeof(unsigned short),1,pFILE);
           fread(&bmfh.bfOffBits,sizeof(unsigned long),1,pFILE);*/

           fclose(pFILE);

           printf("%s\n",argv[1]);
           printf("Type: %hi\nSize: %li\nReserved1: %hi\nReserved2: %hi\nOffsetBits: %li\n\n",
                  bmfh.bfType, bmfh.bfSize, bmfh.bfReserved1, bmfh.bfReserved2, bmfh.bfOffBits);
         }
       else
         {
           printf("Err open!\n");
           return (2);
         }
     }
   else
     {
       printf("Err usage!\n");
       return (1);
     }

   return (0);
 }

-------------------------------------- end ------------------------------------


-- 
Viktor Bresan, student of electronics at FESB Split, Croatia
http://public.srce.hr/~vbresan/