Extension Methods to Reverse a String and StringBuilder Object

This was already decided here in another thread... Using unsafe code and just copying the chars you get much better performance... You could also XOR

charArray[i] ^= charArray[len];
charArray[len] ^= charArray[i];
charArray[i] ^= charArray[len];

But something like this is actually faster due to less operations not allocations.

public static unsafe void Reverse(ref String string)
{
    fixed(char* chars = string)
    {
        int c = 0, d = string.Length - 1;
        while(c < d)
        {
            char t = chars[d];
            chars[d] = chars[c];
            chars[c] = t;
            c++;
            d--;
        }
    }
}

public static void Reverse(ref String string)
{
        char[] chars = string.ToCharArray();
        int c = 0, d = string.Length - 1;
        while(c &lt; d)
        {
            char t = chars[d];
            chars[d] = chars[c];
            chars[c] = t;
            c++;
            d--;
        }    
string = new string(chars);
}