Advanced: Calculate square root with templates

[Sang-drax]

I've decided to host a contest in C++.

This contest involves template metaprogramming, therefore, the language is required to be C++. If you find this task hard, don't worry, because template programming is quite tricky!

The goal is to write a templated struct or class which contains a member which is the square root of the template argument. The struct must be written in this form:

template<int x /*other arguments allowed, but must have default values*/ >
struct SquareRoot
{
static const int v = /* integer part of sqrt(x) */
/*other members allowed*/
};

it must be called 'SquareRoot' and it must have a member called 'v' which contains the integer i for which
i <= sqrt(x) < i + 1
which means that i contains the truncated value of sqrt(x).

Example;

cout << SquareRoot<9>::v; //Must output 3
cout << SquareRoot<1000>::v; //Must output 31
cout << SquareRoot<82>::v; //Must output 9 

//
The following criterias are considered (in order) to determine the winner of the contest:

1. The maximum value of x for which the program compiles (maximum 2^31-1 on my machine) and gives the correct value.
   x will not be smaller than 1.
2. The shortest source code, measured in bytes
3. The time when the email with the solution arrived.

Some other rules:

• It is allowed to 'update' your solution if you find a better one.
• The deadline is Sunday, October, 3rd
• Entries should be mailed to contest@barbapapqa.cjb.net
• My primary compiler is MSVC++.NET; if you use another one, please specify in your entry (please use free compilers).
  Microsofts latest C++ compiler can be downloaded for free here.
• The calculation must be done entirely in the compiler. As an example, this code must be able to compile:
  

  char data[ SquareRoot<16>::v ];
  

After the deadline, it'll probably take a day or two to judge the contest, depending on the number of entries and different compilers used.

The winner will recieve... well... some reputation.

I cannot think of anything more right now.

UPDATE:
The first criteria of judgement is very compiler-dependent. Hopefully, every entry will will compile in the same compiler.

Please post in this thread if you're participating!

These are the people that have submitted entries which complies for at least some values of x:

• Fordy
• Okinrus
• Mr Wizard
• LuckY
• xErath

A number of people (4) have submitted solutions involving the use of std::sqrt. These solutions will not work, because the value of SquareRoot<x>::v must be known at compile time.

[The Brain]

this is outta my league man..

maybe next time

[JaWiB]

Well I have a solution that works, as far as I can tell, according to your guidelines. It's not exactly fast or anything and It's probably not that short either, but it seems to work. I guess I'll send it in and see if I can "update" it later

[Shakti]

Im in.

[Sang-drax]

JaWiB, you should send in your solution.
This problem isn't trivial.

So far, I haven't recieved any (working) solutions.

[JaWiB]

Wait, so you didn't receive mine or it didn't work? I sent it to you the other day...

Edit: I really hope you received it because I have assignments for my english class that I sent in by email, and the first assignment already showed up as a zero for my grades.

[Sang-drax]

Sorry, I haven't recieved anything from you JaWiB. Please resend your entry via PM or email.

[Fordy]

Emailed

[okinrus]

Sure, I'll email my entry to you.

[JaWiB]

>>Sorry, I haven't recieved anything from you JaWiB. Please resend your entry via PM or email.

Ah well I guess there's a bug with gmail then...Not sure what's going on because I can see it in my sent items. I'll try from my yahoo address.

[DavT]

I've only just submitted my entry - bit slow off the blocks...

[PJYelton]

Ok, I sent in my entry.

[MrWizard]

Sent my entry.

[Sang-drax]

I'm unable to update the list of entries, but Mr Wizard's entry works fine.

EDIT: Now I'm able to update

[Fordy]

Originally Posted by Sang-drax

I'm unable to update the list of entries, but Mr Wizard's entry works fine.

I can edit it so if you want to PM me I'll fix the list