Funny C tricks

Taken from Bill Rowan's Stanford ACM presentation:

The "downto" operator:

int main()
{
int i = 5;
while(i --> 0) // --> is the downto operator!
{
  printf("%d\n", i);
}
return 0;
}

Cast any type to "bool" type (that is, 1 or 0):

!!foo

"Computed goto" (compiler-dependent && unary operator):

void print_loop(int s, int e) {
 assert(s < e);   
 top:    
 printf("%d\n", s);  
 goto *( &&top + ( !!(s++/e) ) * ( &&end - &&top ) );    
 end:  
 ;
} 

Browsing as Googlebot to circumvent paywalls

Interesting technique from a Slashdot article and commenter darthflo:

Most 'papers like Google and the visitors Google sends them; so the Google Bot and hits with a google.com Referer tend to get a free pass. Use this to your advantage:

• Google the Article's URI, click the link and off you go (with a real Google referer).
• If it's not indexed yet and you're using Opera: Go to any Google page, press Ctrl + U, change any one link's href to the article's URI, click "Save Changes", click the link and off you go (with a fake Google referer. This works for any fake referer, by the way).
• If they're picky, they mightn't let hits from Google through but still allow the Google bot to index their pages. Change your User-Agent accordingly. In Firefox, go to about:config and change general.useragent.extra.firefox to Googlebot 2.1 and off you go (as Googlebot).
• As a last resort, there's quite a few ad-blocking personal proxies out there. Most of them allow you to fake Referers or change User-Agents, for any browser.