What can go wrong with this code?

[iago]

Then the code works fine.  Skywing is crazy.  

Simply because it appears to work fine doesn't mean that nothing is wrong.

It does, I'm afraid.  So you lose.  

[Grok]

Skywing is correct.  You're not thinking.

[DarkMinion]

Maybe because you're outputting it as unsigned when it returns a signed integer?

[DarkMinion]

Also, getc() returns a signed integer as well...could lead to certain problems

[Skywing]

Maybe because you're outputting it as unsigned when it returns a signed integer?

That's not the problem in question.  Outputting an int as unsigned isn't the cause of any breakage here.

[DarkMinion]

Maybe it would help if you said what problem you were experiencing?  Ballpark?

[iago]

To quote the man page:

GETS(3)             Linux Programmer's Manual             GETS(3)

NAME
      fgetc, fgets, getc, getchar, gets, ungetc - input of char-
      acters and strings

SYNOPSIS
      #include <stdio.h>
[...]
      int getc(FILE *stream);

getc returns and int and your storing it in a char.  Bad?

[Skywing]

Maybe it would help if you said what problem you were experiencing?  Ballpark?

The problem isn't related to the printf call failing or outputting the return value of isspace incorrectly because I used %u.  For instance, the same problem would occur if you were using C++ and did std::cout << isspace(ch) << endl;.  I'm not sure what else I can say without giving it away.

[DarkMinion]

Bad iago copying what I just said.

[iago]

Bad iago copying what I just said.

Not really.. I actually said what the problem IS.  

[Skywing]

Note that the topic is What can go wrong with this code? and not What does this code do wrong?.  If you see something that you think is wrong, you should be able to tell about the consequences of that and soforth...

[iago]

Well, if getc returns something greater than 255 (I don't know how this would happen, but it CAN since it's an <int>), it will overflow the char.  I don't think anything with break, besides getting an invalid value in ch.

[Skywing]

Well, if getc returns something greater than 255 (I don't know how this would happen, but it CAN since it's an <int>), it will overflow the char.  I don't think anything with break, besides getting an invalid value in ch.

I think that in the case of an overflow, ch will get the return value of getc modulo max_value_of_char, possibly adjusting for signedness.  In any case, I don't think it'll have an "invalid" value (assume all values of a char are "valid" characters).

[DarkMinion]

Actually iago, you really did just say what I just said

But according to Sky, it's wrong

[iago]

True, but if you press character 0x120 (look carefully, it's in the corner), and it modulos it by sizeof(char), it will incorrectly identify it as a space.

Another thing I was thinking, \n is made up of 2 characters on some computers; will that affect the output, or is 0x0d 0x0a read in as a single character?

[edit] fixed \n hex.. oops