C#

public void Main()
{
    string foo = "i will do my homework on my own";
    string blah = reverseString(foo);
    Console.WriteLine(foo);
    Console.WriteLine(blah);
}
public void reverseString(string Text)
{
    System.Collections.Stack st = new Stack();
    foreach (char c in Text)
    {
        st.Push(c);
    }
    ArrayList l = new ArrayList();
    while (st.Count > 0)
    {
        l.Add(st.Pop());
    }
    char[] s = l.ToArray(typeof(char)) as char[];
    string RetVal = new string(s);
    return RetVal;
}

hustler2005 wrote:

for (int i = lengthOfArray; i < 0; i--)

public void Main()
{
    string str = "I will do my homework on my own";
    IntPtr strPtr = Marshal.StringToHGlobalUni(str);
    IntPtr resPtr = ReverseString(strPtr);
    string res = Marshal.PtrToStringUni(result);
    Marshal.FreeHGlobal(strPtr);
    Marshal.FreeHGlobal(resPtr);
    Console.WriteLine(str);
    Console.WriteLine(res);
}


public IntPtr ReverseString(IntPtr strPtr)
{
    string str = Marshal.PtrToStringUni(strPtr);
    char[] strAsCharArray = new char[str.Length];
    for (int i = 0; i < str.Length; ++i)
    {
        strAsCharArray[i] = str[0];
        str = str.Substring(1);
    }
    StringBuilder sb = new StringBuilder(strAsCharArray.Length);
    string res = string.Empty;
    for (int i = 0; i < str.Length; i += 2)
    {
        string next = string.Empty;
        for (int j = 1; j >= 0; --j)
        {
            if (i + j == str.Length)
                continue;
            char c = strAsCharArray[i + j];
            next.Insert(0, c.ToString());
            res.Insert(1 - j, c.ToString());
        }
        sb.Append(next);
    }
    str = sb.ToString();
    IntPtr rval = Marshal.StringToHGlobalUni(res);
    return rval;
}

public string ReverseString(string str) {
    StringBuilder result = new StringBuilder();
    for (int i = str.Length - 1; i >= 0; --i)
        result.Append(str[i]);
    return result.ToString();
}