Quickest Method to Reverse in String in C#.net

Question

I\'m currently writing a quick solution for Euler Problem #4 where one must find the largest palindromic number from the product of two 3-digit numbers.

To identify if a

Answer 1

The fastest way I have found to reverse a string in C# is with the following code. It's faster reading in 32bits at a time instead of a char's length of 16bits. In debug mode, it is faster until you get to about 93 characters. Anything longer than that Array.Reverse() is faster. Using a release build and running outside of the IDE, this method will blow Array.Reverse() out of the water at any string length.

char[] MyCharArray = MyString.ToCharArray();
UIntStringReverse(ref MyCharArray);     //Code to reverse is below.
string ReversedString = new string(MyCharArray);


private static unsafe void UIntStringReverse(ref char[] arr)
{
    uint Temp;
    uint Temp2;

    fixed (char* arrPtr = &arr[0])
    {
        uint* p, q;
        p = (uint*)(arrPtr);
        q = (uint*)(arrPtr + arr.LongLength - 2);

        if (arr.LongLength == 2)
        {
            Temp = *p;
            *p = ((Temp & 0xFFFF0000) >> 16) | ((Temp & 0x0000FFFF) << 16); 
            return;
        }

        while (p < q)
        {
            Temp = *p;
            Temp2 = *q;

            *p = ((Temp2 & 0xFFFF0000) >> 16) | ((Temp2 & 0x0000FFFF) << 16); 
            *q = ((Temp & 0xFFFF0000) >> 16) | ((Temp & 0x0000FFFF) << 16);

            p++;
            q--;
        }
    }
}