Vugen: Will This Code Remove Trailing Spaces?

Let’s have a little fun today – and hopefully I can get some interaction from you C Guru’s out there. How about something cryptic in C? Let’s say I wanted to remove some trailing spaces with as few lines of C code as possible. Will the example below work?

static char* rtrim( char* s)
 {
 int i;
 if (s){i = strlen(s); while ((--i)>0 && isspace(s[i]) ) s[i]=0;}
 return s;
 };

Why or why not? Care to explain what this code is doing? Comments are open and welcome.