Tuesday, March 31, 2009

What is the worst feature of C?

This was a question on the Google Summer of Code application template for the CCAN (Comprehensive C Archive Network) organization.

C's problem is not a "feature" per se. To understand what is wrong with C, you have to ask why it takes six lines or more to do simple things like retrieve a single line from the console and convert it to an integer:
char buffer[32];
printf("prompt> ");
fgets(buffer, sizeof(buffer), stdin);
if (*buffer==0 || *buffer=='\n')
num = atoi(buffer);
By comparison, in Perl it'd be:
num = int(<>);
C suffers from stagnancy. If one wants to create a directory, he/she or he\she has to worry about conflicting standards. Functions for creating and traversing through directories are not standardized across the major platforms. Unix doesn't even have a function call for copying a file (if you do it the manual way with fread/fwrite, that still doesn't compensate for sparse files). Even the language itself has similar issues. Can I use typeof or not? Is long 32 or 64 bits? Is long long even available? I need not discuss creating a window or displaying an Open dialog.

How do programmers deal with this? Most flock to Java, Python, and other low-performance languages. Others rely on toolkits such as Qt to abstract those details while sacrificing the portability of C. Few put up with it by learning the details, and even when they do, they end up with messy (and likely still incorrect) code.

Nevertheless, C has crucial benefits. It is the lingua franca of compiled programming languages. If you write a library in C, it can easily be adapted for use in C++, D, eC, etc.. Most importantly, C and its compile-to-machine-code brethren are fast. If you want an operating system package manager to be quick, you write it in C, not Python.

The reason it is so hard to program in C is because C has an inadequate, obsolete standard library. I believe CCAN, by providing a standard repository for C libraries (analogous to CPAN for Perl and Boost for C++), will soundly overcome this obstacle.


I probably should have started a blog long ago. I've oft wanted to rant about random stuff, and I tended to dump my ideas into IRC and forums. Now that I have some necessity for a blog, a better understanding of what a blog is, and have noticed that many of my Google searches for help land me on blogs, I too have a blog that I hope will be useful to many.

I will probably talk mostly about programming (mainly C) and Linux, though other topics may come to mind. I will never ever cuss on this blog, nor do I plan to say anything worse than "crap" or "drugs". Feel free to let your mother, grandmother, kids, and teacher/boss who's standing right behind you read this blog (if they're interested).

To round up this post and to round up some hits, here's a simple routine in C for randomly scrambling an array:
void scramble(void *base, size_t nmemb, size_t size) {
char *i = base;
char *o;
size_t sd;
for (;nmemb>1;nmemb--) {
o = i + size*(random()%nmemb);
for (sd=size;sd--;) {
char tmp = *o;
*o++ = *i;
*i++ = tmp;
Note that it has horrendous cache performance for large arrays.