Thread: How do you catch a read error from stdin?

Hi guys!

My program basically reads from a text file or whatever is piped into it through std in and I need to catch a read error, but I'm confused on what to even look for exactly.

Someone would run my program like this:
myProgram < aTextFile.txt

Here is some of my code what does the reading:

Code:

 while ((c = getc(stdin)) != EOF)
 76     {
 77       /*counting characters*/
 78       characters++;
 79 
 80       /*counting special characters*/
 81       if(isprint(c) != 0)
 82         printable++;
 83       if(iscntrl(c) != 0)
 84       {
 85         control++;
 86       }
 87       if(c == '\n')
 88        newline++;

As you can see i'm just using getc to read each character, but what would I check if there was an error reading the file? if an error did occur I would just exit(1) but what to check for is where I'm lost.

Thanks!

If there's a read error, fgetc will return EOF. (Note: typing man fgetc would have gotten you the same information.)

Keep reading:

Originally Posted by man getc

If successful, these routines return the next requested object from the
stream. Character values are returned as an unsigned char converted to
an int. If the stream is at end-of-file or a read error occurs, the rou-
tines return EOF. The routines feof(3) and ferror(3) must be used to
distinguish between end-of-file and error. If an error occurs, the
global variable errno is set to indicate the error. The end-of-file con-
dition is remembered, even on a terminal, and all subsequent attempts to
read will return EOF until the condition is cleared with clearerr(3).

Naturally, feof returns true if eof happened, and ferror returns true if error happened.

Thanks guys!
I ended up using code like this:

Code:

if(ferror(stdin))
  printf("bad things to say");
   exit(1);

Originally Posted by mr_coffee

Thanks guys!
I ended up using code like this:

Code:

if(ferror(stdin))
  printf("bad things to say");
   exit(1);

That exit()s unconditionally.