请哪位熟悉的帮忙把C#代码转为VC代码

private const string mstr = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

public static string EnCode(string str)
{
if (string.IsNullOrEmpty(str))
{
return "";
}

byte[] buff = Encoding.Default.GetBytes(str);
int j, k, m;
int len = mstr.Length;
StringBuilder sb = new StringBuilder();
Random r = new Random();

for (int i = 0; i < buff.Length; i++)
{
j = (byte)r.Next(6);
buff[i] = (byte)((int)buff[i] ^ j);
k = (int)buff[i] % len;
m = (int)buff[i] / len;
m = m * 8 + j;
sb.Append(mstr.Substring(k, 1) + mstr.Substring(m, 1));
}

return sb.ToString();
}

public static string DeCode(string str)
{
if (string.IsNullOrEmpty(str))
{
return "";
}

try
{
int j, k, m, n = 0;
int len = mstr.Length;
byte[] buff = new byte[str.Length / 2];

for (int i = 0; i < str.Length; i += 2)
{
k = mstr.IndexOf(str[i]);
m = mstr.IndexOf(str[i + 1]);
j = m / 8;
m = m - j * 8;
buff[n] = (byte)(j * len + k);
buff[n] = (byte)((int)buff[n] ^ m);
n++;
}
return Encoding.Default.GetString(buff);
}
catch
{
return "";
}
}