Deconstructing "K&R C"

Post by blix » Tue, Jan 10, 2012, 11:14 PM UTC

geophile wrote: post #30

tba wrote: post #8

I'm confused. What is the "defect" in K&R's "copy(char to[], char from[])" function? The author notes that "the second this function is called...without a trailing '\0' character, then you'll hit difficult to debug errors", but no function with that signature could possibly work in this case. The built-in "strcpy" function has the exact same limitation. Does the author have a problem with it as well? Null-termination…

Huh? My C programming is in the distant past, so I might be forgetting. But strcpy does assume a terminal zero, doesn't it? E.g., http://linux.die.net/man/3/strcpy . It sounds like you are talking about strncpy or memcpy.

Post by scott_s » Tue, Jan 10, 2012, 11:26 PM UTC

adavies42 wrote: post #20

> Braces Are Free, Use Them I disagree. Braces have a cognitive load, particularly if they're given whole lines to themselves. Which is easier to read, while ((len = getline(line, MAXLINE)) > 0) if (len > max) { max = len; copy(longest, line); } if (max > 0) /* there was a line */ printf("%s", longest); or while ((len = getline(line, MAXLINE)) > 0) { if (len > max) { max = len; copy(longest, line); } } if (max > 0) /…

  while ((len = getline(line, MAXLINE)) > 0) {
      if (len > max) {
          max = len;
          copy(longest, line);
      }
  }
  if (max > 0) { /* there was a line */
      printf("%s", longest);
  }

Post by mechanical_fish » Tue, Jan 10, 2012, 11:39 PM UTC

peapicker wrote: post #19

mechanical_fish wrote: post #17

Earlier quoted context omitted.

The built-in "strcpy" function has the exact same limitation. Does the author have a problem with it as well? Yes. From the linked chapter: we avoided classic style C strings in this book From an earlier chapter on strings: The source of almost all bugs in C come from forgetting to have enough space, or forgetting to put a '\0' at the end of a string. In fact it's so common and hard to get right that the majority of…

"the majority of good C code just doesn't use C style strings..." Nice. In the 23 years I have worked on C language products, I've never worked on "good C code" by this definition. The cool thing about this guys book, I guess, is that by avoiding all the things about the language he doesn't like, any reader will be wholly unprepared for C in the Real World after this book.

Post by [deleted] » Tue, Jan 10, 2012, 11:50 PM UTC

tba wrote: post #8

I'm confused. What is the "defect" in K&R's "copy(char to[], char from[])" function? The author notes that "the second this function is called...without a trailing '\0' character, then you'll hit difficult to debug errors", but no function with that signature could possibly work in this case. The built-in "strcpy" function has the exact same limitation. Does the author have a problem with it as well? Null-termination…

Post by glitch » Wed, Jan 11, 2012, 12:02 AM UTC

SeanLuke wrote: post #24

adavies42 wrote: post #20

> Braces Are Free, Use Them I disagree. Braces have a cognitive load, particularly if they're given whole lines to themselves. Which is easier to read, while ((len = getline(line, MAXLINE)) > 0) if (len > max) { max = len; copy(longest, line); } if (max > 0) /* there was a line */ printf("%s", longest); or while ((len = getline(line, MAXLINE)) > 0) { if (len > max) { max = len; copy(longest, line); } } if (max > 0) /…

I'm probably the last person in the world to prefer: while ((len = getline(line, MAXLINE)) > 0) if (len > max) { max = len; copy(longest, line); } if (max > 0) /* there was a line */ printf("%s", longest); I fear this may be literally true: this brace style is called Whitesmith's, and I was reporting bugs to the cc-mode indenter for emacs a while ago. BSD/Allman and K&R styles never made sense to me.