Xref: news2.mv.net comp.os.msdos.djgpp:6355
Newsgroups: comp.os.msdos.djgpp
From: Robert Jaycocks <r DOT jaycocks1 AT lut DOT ac DOT uk>
Subject: Re: C Program crashes in Djgpp
Sender: usenet AT lboro DOT ac DOT uk (Usenet-News)
Message-ID: <31F619EE.424A@lut.ac.uk>
Date: Wed, 24 Jul 1996 12:41:18 GMT
To: PENG ZHOU <pengzh AT ix DOT netcom DOT com>
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DJ-Gateway: from newsgroup comp.os.msdos.djgpp

PENG ZHOU wrote:
> 
> Hi,
>     My program fileread.c which works ok with my MSC but crashes with
> some general protection faults in DJGPP.  Don't know why.
> 
> --------------------FileRead.c----------------------
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> 
> int main(int argc, char **argv)
> {
>   FILE *input;Change this to FILE *input = NULL;  (See below for explanation. )
>   char ch;
>   int arr;
> 
>   for ( arr = 0; arr < argc; arr++ )

This should be for (arr = 1;arr < argc;arr++). argv[0] is the program
name.

>   {
>     if ( (strcmp(argv[arr],"-help)==0) || (strcmp(argv[arr],"-h")==0) )
>     {
>       puts("FileRead.EXE v.1\n");
>       puts("Usage: C>FileRead -file filename.xxx\n");
>       exit(0);
>     }
> 
>     if ( (strcmp(argv[arr],"-file)==0) || (strcmp(argv[arr],"-f")==0) )
>     {
>       input = fopen(argv[arr+1], "r");
>       if ( input == NULL )
>       {
>         puts("Cannot open file!\n");
>         exit(1);
>       }
>     }
>   }
>

What happens when there are no arguments. input is not set correctly.
Initially set input to NULL, then add an if statement before this:

  if(input != NULL)
  { 
>   while (!feof(input))
>   {
>     ch = getc(input);
>     printf("%c", ch);
>   }
>   fclose(input);  }
>   return 0;
> }
> 
> This program might have a few bugs but it runs ok in MSC, compiles ok
> in DJGPP but crashes when runned.  Any Suggestions?
> 
> ----
> pengzh AT ix DOT netcom DOT com
> 
> 
> Apart from the points I mentioned above, I cannot see any other errors.

Robert