Re: Right shift >> weird result... Why?

OK, the solution to this is probably blindingly obvious to everyone,
but... surely it can't be right.

I am compiling with borland bcc32 free compiler

this piece of code is designed to identify the most significant bit in
a given element in an array of unsigned longs. Now I realise there
may be a more efficient way to do this, and if you know a better way
please let me know.

However, the efficieny of the code is neither here nor there, the
point is the weird result:

// an array of two unsigned longs
unsigned long twoULongs[2];

// initial amount to shift by
unsigned long rShift = 0;

// fill the lowest element of the array with its maximum
               // possible value
twoULongs[0] = 0xFFFFFFFF;
twoULongs[1] = 0;

// this loop should end when we have discovered the most significant
bit in
               // element 0 of the array storing the bit number in
rShift
               // (actually, the bit position + 1)
while((twoULongs[0] >> rShift) != 0)
{
// Display the value of the shift (for debug purposes)
cout << (twoULongs[0] >> rShift) << endl;
// since we haven't found the msb yet, shift by one more next time
rShift++;
// pause the program so we can see whats going on for debug
                               // purposes
cin.get();
}

Now the output, as twoULongs[0] tends towards 0 is:

31, 15, 7, 3, 1, 4294967295 !!!

Whoa!! we just ticked over back to the highest possible unsigned
long!!!

So why didn't it hit 0 after 1?

please rate my idiocy, and if you know whats wrong, tell me