Thread: a proper read loop

I've been reading characters from text files but I have been using a loop that uses

Code:

	while(!feof(filename))

to read into whatever I want it to read into. However, I know this is not the proper way to do it.

I'm supposed to be using the return code of whatever I am using to read from the file, right?

So I am using fscanf and reading 1 character at a time....how do I loop with fscanf? I guess my question is what does fscanf return when it reaches the end of a file. The code below is simply what my guess is at what it will be like.

Code:

while( (fscanf(filename, "%c", &next_char) != ???) )
{
    work with data here
}

Thanks.

I have that page bookmarked from before but I'm still at a stage where I dont understand alot of what those manual pages are really saying. Thanks though...I'm getting there.

The value EOF is returned if an input failure occurs before any conversion such as an end-of-file occurs.

That was from the refrence site Hammer told you to look at.

So you would want to use:

Code:

 while( (fscanf(filename, "%c", &next_char) != EOF) )

Originally posted by GravtyKlz
That was from the refrence site Hammer told you to look at.

So you would want to use:

Code:

 while( (fscanf(filename, "%c", &next_char) != EOF) )

Also from the same site:

Code:

RETURN VALUES
       These functions return the number of input items assigned,
       which can be fewer than provided for, or even zero, in the
       event  of  a matching failure.  Zero indicates that, while
       there was input available, no conversions  were  assigned;
       typically  this is due to an invalid input character, such
       as an alphabetic character for  a  `%d'  conversion.   The
       value  EOF  is  returned if an input failure occurs before
       any conversion such as an end-of-file occurs. If an  error
       or end-of-file occurs after conversion has begun, the num-
       ber of conversions which were  successfully  completed  is
       returned.

I'd do it like this.

Code:

#include <stdio.h> 
int main()
{
   const char filename[] = "test.txt";
   FILE *file = fopen(filename, "r");
   if ( file != NULL )
   {
      char ch;
      while ( fscanf(file, "%c", &ch) == 1 )
      {
         /* do stuff */
         putchar(ch);
      }
      fflush(stdout);
      fclose(file);
   }
   return 0;
}

Or this.

Code:

#include <stdio.h> 
int main()
{
   const char filename[] = "test.txt";
   FILE *file = fopen(filename, "r");
   if ( file != NULL )
   {
      for ( ;; )
      {
         int ch = fgetc(file);
         if( ch == EOF )
         {
            break;
         }
         /* do stuff */
         putchar(ch);
      }
      fflush(stdout);
      fclose(file);
   }
   return 0;
}