EOF does not work in Mac Xcode (C)?

Question

I am currently running this character counting .c but the EOF is not reached unless I press control D, which is very annoying.

#include <stdio.h>
main () {

   long nc;

   nc = 0;

   while (getchar() != EOF) {
       ++nc;
   }

   printf("%ld\n", nc);

}

@SouravGhosh `int main(int argc, char **argv)` if you want to get picky about it. — , Jun 16 '17 at 06:18
@DaanTimmer: EOF is right, see manpage: `reads the next character from stream and returns it as an unsigned char cast to an int, or EOF on end of file or error.` — Andre Kampling, Jun 16 '17 at 06:19
@duskwuff: There's no need to use the argc/argv form for `main()` when the program ignores the command line arguments. Both `int main(void)` and `int main(int argc, char **argv)` are explicitly OK. — Jonathan Leffler, Jun 16 '17 at 06:30
@JonathanLeffler At the time I replied, SouravGhosh's comment was recommending `int main()`, with no argument list. — , Jun 16 '17 at 07:37
@duskwuff: I'm not sure I understand. It probably doesn't matter. I'll clean up my comments later. — Jonathan Leffler, Jun 16 '17 at 07:40

Ajay Brahmakshatriya · Accepted Answer · 2017-06-16T06:49:18.897

3

What you are seeing is the expected behavior.

EOF is encountered only when the input stream ends. What you are doing (I suppose) is press the enter key. That doesn't signal EOF, because you could type in more stuff after the enter. Ctr+D signals the end of a file.

What you can do is look for End Of Line. And you also need to look for EOF since the user can terminate by pressing Ctr+D (as suggested by @DavidC.Rankin)

This can be done by matching getchar() with '\n' and EOF as

int c
while ((c = getchar()) != '\n' && c != EOF) {
    ++nc;
}

Hope this helps.

edited Jun 16 '17 at 06:49

answered Jun 16 '17 at 06:22

Ajay Brahmakshatriya

8,993
3
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49

What happens if the user presses `Ctrl+d` (or `ctrl+z` on windoze)? (you need to check both `'\n'` && `EOF`) (e.g. `int c; while ((c = getchar()) != '\n' && c != EOF) ...`) – David C. Rankin Jun 16 '17 at 06:34
@DavidC.Ranakin, oh yes. I will fix it. – Ajay Brahmakshatriya Jun 16 '17 at 06:38
@DavidC.Rankin: You have to check both like this: `char readChar; while ((readChar = getchar()) != EOF && readChar != '\n') { ... }` – Andre Kampling Jun 16 '17 at 06:38
Only if your implementation defines `EOF` as type `char`, otherwise `EOF` (`-1` generally) will never be seen on a little-endian box. – David C. Rankin Jun 16 '17 at 06:39
@DavidC.Rankin, corrected! Also is that fancy spelling for "windoze" intentional? :p – Ajay Brahmakshatriya Jun 16 '17 at 06:45
1

(tongue-in-cheek) yep, it's just a light-hearted dig at the windows crowd. (I don't have anything against any OS, but do prefer not to rent software...) – David C. Rankin Jun 16 '17 at 06:47
@AndreKampling See: See: [**Comparing unsigned char and EOF**](https://stackoverflow.com/questions/8586722/comparing-unsigned-char-and-eof) for an explanation of why it should be `int` . (because `getchar` reads each char as an `unsigned char` cast to an `int` which would result in the comparison of `if (0x000000ff == 0xffffffff)` in your case) – David C. Rankin Jun 16 '17 at 06:57
@DavidC.Rankin: Thank you for your hint! – Andre Kampling Jun 16 '17 at 06:59

EOF does not work in Mac Xcode (C)?

1 Answers1