Test your skills (2006)

[wtd]

Io TYS.

code:

Io> foo(a, 42, a print) 42 ==> 42 Io> foo(i, "foo", i with("!") print) foo! ==> foo!

Write a method which makes the above possible.

code:

Io> foo := method(        /* your code here */     )

[wtd]

Write a function which appends lists.

code:

(defun list-append (...) ...)

A few samples:

code:

(list-append '(1 2 3) '(4 5 6))    ; (1 2 3 4 5 6) (list-append '(1 2) '(3 4) '(5 6)) ; (1 2 3 4 5 6)

You may use the following functions or macros.

• flet
  
• cons
  
• car
  
• cdr
  
• if
  
• defun (but only the one, in the code I already demonstrated)
  
• reduce

You may very explicitly not use the loop macro.

You may not have any code outside of the list-append function.

[wtd]

C++ gurus: a TYS just for you.

Explain why this code will not compile.

code:

#include <list> #include <vector> int main() {    std::vector<std::list<int>> foo;    return 0; }

[Martin]

C/C++ (or Java). Complete this function to determine if n is a power of 2.

c:

int isPowerOfTwo (int n) {     return <your code!>; }

c++:

bool isPowerOfTwo (int n) {     return <your code!>; }

Java:

boolean isPowerOfTwo (int n) {     return <your code!>; }

[Andy]

c++:

bool isPowerOfTwo (int n) {     return n % 2 ? n == 1 : isPowerOfTwo(n/2); }

does that count as cheating? lol

[Martin]

There's a much better way.

Think bitwise.

[Andy]

haha yea, i was going to do it bitwise, but then i got lazy =P, if i have time, i'll do it at work tomorow

[bugzpodder]

c++:

bool isPowerOfTwo (int n) {     return n<0?0:(n^(n-1))==-1; }

[bugzpodder]

code:

#include <list> #include <vector> int main() {    std::vector<std::list<int>> foo;    return 0; }

>> is an operator in C++. need a space in between.

[wtd]

bugzpodder wrote:

code:

#include <list> #include <vector> int main() {    std::vector<std::list<int>> foo;    return 0; }

>> is an operator in C++. need a space in between.

Yes, that is the solution. But why is it a problem?

[bugzpodder]

? its a problem because >> is a predefined operator in C++. But i thought I've already said that.

[wtd]

But surely C++ compilers can tell the difference?

[bugzpodder]

clearly not? lol

[Martin]

bugzpodder wrote:

c++:

bool isPowerOfTwo (int n) {     return n<0?0:(n^(n-1))==-1; }

Another one is.

c++:

bool isPowerOfTwo (int n) {     return n?(n &-n)==n:0; }

[wtd]

bugzpodder wrote:

clearly not? lol

code:

some_value >> some_other_value

Could clearly never be a type. So... why does C++ get confused?