Question

I need to convert a few lines of PHP code to C#. However, I have only basic knowledge and I don’t understand well the arrays yet.

Here is the code that I need to be converted to C#:

function decode_char($c, $a1, $a2)
{
  $result = $c;
  for($j = 0; $j < count($a1); $j++) {
    if ($c == $a1[$j][0]) {
      $result = $a2[$j][0];
      break;
    }
    if ($c == $a2[$j][0]) {
      $result = $a1[$j][0];
      break;
    }
  }
  return $result;
}

function decode_str($s)
{
  $a1 = array("0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "W", "G", "X", "M", "H", "R", "U", "Z", "I", "D", "=", "N", "Q", "V", "B", "L");
  $a2 = array("b", "z", "a", "c", "l", "m", "e", "p", "s", "J", "x", "d", "f", "t", "i", "o", "Y", "k", "n", "g", "r", "y", "T", "w", "u", "v");

  $result = '';
  for($i = 0; $i < strlen($s); $i++) {
    $result .= decode_char($s[$i], $a1, $a2);
  }
  $result = base64_decode($result);
  return $result;
}

Here’s what I’ve got so far:

public string decode_str(string s)
{
       string[] a1 = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "W", "G", "X", "M", "H", "R", "U", "Z", "I", "D", "=", "N", "Q", "V", "B", "L" };
       string[] a2 = { "b", "z", "a", "c", "l", "m", "e", "p", "s", "J", "x", "d", "f", "t", "i", "o", "Y", "k", "n", "g", "r", "y", "T", "w", "u", "v" };

       string result = "";
       for (int i = 0; i < s.Length; i++)
       {
           result += decode_char(s[i], a1, a2);
       }

           return result;
}

Can someone help with converting decode_char?

Thank you for fast answers. I already did it myself but using strings and not chars, so I will accept an answer tomorrow when I will revise my code.

Answer 1

Try with this:

char decode_char(char c, string a1, string a2)
{
    for (int i = 0; i < a1.Length; i++)
    {
        if (c == a1[i]) return a2[i];
        if (c == a2[i]) return a1[i];
    }
    return c;
}
string decode_str(string s)
{
    const string a1 = "0123456789WGXMHRUZID=NQVBL";
    const string a2 = "bzaclmepsJxdftioYkngryTwuv";
    StringBuilder sb = new StringBuilder();
    foreach (char c in s)
        sb.Append(decode_char(c, a1, a2));
    return DecodeFrom64(sb.ToString());
}
string DecodeFrom64(string encodedData)
{
    byte[] encBytes = Convert.FromBase64String(encodedData);
    return Text.Encoding.Unicode.GetString(encBytes);
}