in-place String reversal

gistfile1.c

void strrev(char *p) {
     char *q = p;
     while(q && *q) ++q; //get last char of the string     
     for(--q; p < q; ++p, --q) {
          *p = *p ^ *q, //xor p
          *q = *p ^ *q, // xor np w/ q to store p's value in q
          *p = *p ^ *q; //xor np w/ nq to get q's original value in p
     }   
}