Re: The contents of the file is not read..

[Steve Kemp <skx@debian.org>]

On Tue, Nov 07, 2006 at 06:19:59PM +0530, Naga Priya .K wrote:

> i'm a beginner in C.  I used the following code to read and print the 
> strings in  a file. but  the control doesn't reach inside the while 
> loop. what is the problem?

  The problem is that you don't initialise things correctly.  You
 test against "EOF" but don't set it anywhere.

> FILE *FilesRead=fopen("FilesRead.txt","r");
>    if(!FilesRead)
>        printf("File not opened");
>    else
>        printf("Opened file");

  This is wrong, since if the file open fails you still continue.
 Try this:

   FILE *f = fopen( "FilesRead.txt", "r" );
   if ( !f )
   {
      printf(" Failed to open file\n" );
      exit( 1 );
   }


>    while(!EOF)
>    {
>        fscanf(FilesRead,"%s",name_read);
>        printf("%s",name_read);
>    }
>    fclose(FilesRead);

  You don't change EOF so this will most likely not work.  Try this:

   while( ! feof( f ) )
   {
     ..
   }

  Note that you don't define name_read, and you also don't take into
 account what will happen if "too much" is read.

  See attached version beneath my sig for a working, albeit not
  attractive, program.

  In the future these questions would be better posted in the comp.lang.c
 newsgroup or similar .. since they are not debian-specific.

Steve
-- 
# The Debian Security Audit Project.
http://www.debian.org/security/audit


#include <stdlib.h>
#include <stdio.h>


int main( int argc, char *argv[] )
{
    char line[1024];

    FILE *f = fopen( "FilesRead.txt", "r" );
    if ( !f )
    {
        printf(" Failed to open file\n" );
        return 1;
    }

    while( ! feof( f ) )
    {
        /* Fill buffer with NULL, and make sure we don't read more than 1000
           characters.  Buffer overflow protection. */
        memset( line, '\0', sizeof(line ) );
        fscanf( f, "%1000s", &line );
        printf( "Read: %s\n", line );
    }
    fclose( f ) ;

    return 0;
}