NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/lang/c/16784

Text File | 1992-11-19 | 2.7 KB | 87 lines

Newsgroups: comp.lang.c
Path: sparky!uunet!cs.utexas.edu!torn!csd.unb.ca!elara.sun.csd.unb.ca!d0np
From: [e-mail] (Godzilla)
Subject: Re: fwrite & fread
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: University of New Brunswick
References:  <[e-mail]>
Date: Thu, 19 Nov 1992 13:15:29 GMT
Lines: 75

#In article <[e-mail]>, <[e-mail]> writes:
|> I am using write & fread to read and write to a file. The structure that I
|> am writing has 194 bytes. After executing fwrite I check the value, in vari
|> able a which is 1 (correct), because I am writing one structure. Then I check
|> the values of returned by fclose and ferror and they are also correct i-e 0.
|> But when I quit from the program without writing more structures or without
|> running any other functions and look for the size of my file it shows that it
|> has 414 bytes. Actually, it should have 194 bytes. I have tried with different
|> file modes, but that doesn't solve the problem. I have also tried with a file
|> initially empty and with a file having some records. Therefore, I tried clearin
|> g the buffer, but that also doesn't help. For those of you who might be interes
|> ted in the code, I have it below. Don't pay attention towards syntax errors.
|> I have also included a part of my header file which contains the structure.
|> Thanks in advance,
|> Sikander Waheed    email: [e-mail]
|>
|> #include <stdio.h>
|>
|> #include <stdlib.h>
|> typedef struct activity{
|>     int  id;
|>     int  mm;
|>     int  dd;
|>     int  yy;
|>     char day[10];
|>     int  hour;
|>     int  min;
|>     int  end_hour;
|>     int  end_min;
|>     char location[25];
|>         char with_who[20];
|>     char phone[11];
|>     char subj[30];
|>     char note[300];
|>         int  flag;
|> };
|>
|> void add()
|> {
|> int a,mm,dd,yy,hour,min,st_hour, end_min = 0 , t2_hour, t2_min, i = 0, ok;
|> char ch;
|> FILE *file_pointer;
|> struct activity temp;
|>  ok = busy(mm, dd, yy, hour, t2_hour);
|>  if(ok == 1)
|>    {
|>
          .
          . (stuff deleted)
          .

|>      a = fwrite(&temp, sizeof(temp), 1, file_pointer);

You are writing out sizeof(temp) number of bytes, and since temp is a
struct activity, which has 300+30+11+20+25+10+9*2 = 414 bytes assuming
int is 2 bytes.  Try printing sizeof(temp) to see what you get.

|>      a = ferror(file_pointer);
|>      a = fclose(file_pointer);
|>      a = ferror(file_pointer);
|>      setvbuf(file_pointer, NULL , 194, _IOFBF);
|>      ch = getchar();
|>      } /* end if */
|>     return;
|> }
|>
|>


                                    Hope this helps
                                       Mike


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