Reverse a string in place by using recursion.

// Reverse a string in place by using recursion.
void revstr_r(char *str) {
revstr_recursive(str, 0, strlen(str)-1);
}

void revstr_recursive(char *str, int start, int end) {
if(start < end)
revstr_recursive(str, start+1, end-1);
else
return;
char t = str[start];
str[start] = str[end];
str[end] = t;
}