CryptoGraphic Message

Question

HELLO FRIENDS,
I m creating a CRYPTOGRAPHY WINDOWS FORM APPLICATION.
1-Calculate String Length. (ALREADY DONE)
2-Reverse the String. (ALREADY DONE)
3-Total Length of the message will be save and each character of the message will be replaced from it. (HELP REQUIRED)
Example:
You wrote a message " A CAT"
so STEP 1: calculate Length : 5
STEP 2: reverse : TAC A
STEP 3 : String length is added: so 5 is added to each corresponding character
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Therefore,
A is at 1 , when 5 is added it will become F which is 6,
C is at 3, when 5 is added it will become H, which is 8,
A is again replaced with F
T is at 20, when 5 is added it will become Y, which is 25
Therefore, A message "A CAT" will become " F HFY"
So far i done that:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public string UIT_CRYPTOGRAPHY()
{
string userString = richTextBox1.Text;
char[] textArray = userString.ToCharArray();
int stringLength = userString.Length;
Array.Reverse(textArray);
label1.Text = new string(textArray);
return label1.Text;
}
private void button3_Click(object sender, EventArgs e)
{
/* string[] stringArray = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z" };*/
string ReverseString = UIT_CRYPTOGRAPHY();
label1.Text = ReverseString;
}
PLEASE HELP ME
THANKS IN ADVANCE.

prince shils · Answer

ThankYou Sam Hobbs, I did it.

prince shils · Answer

Oh Brilliant!!, Yes I did, ThankYou Vulpes.

Sam Hobbs · Answer

I am not sure what you need. I hope the following is headed in the correct direction. This does not check what character it is and it does not do wrap-around as Vulpes is doing. I am not sure if you want to limit this to specific characters.
int n = richTextBox1.Text.Length;
StringBuilder sb = new StringBuilder (n);
for ( int i = n - 1; i >= 0; --i)
sb.Append(( char )(richTextBox1.Text[i] + n));
label1.Text = sb.ToString();

Vulpes · Answer

You have two problems there:
1. You need to wrap around if k is less than 65 rather than if k is more than 90.
2. You need to reverse the string after the above manipulation rather than before it.
You can do all this in the Decode button Click handler alone:
private void btnDecode_Click(object sender, EventArgs e)     {         string DecodeString = label1.Text.ToUpper();         int len = DecodeString.Length;         char[] decrypted = new char[len]; // create an array to hold the decrypted characters         for (int i = 0; i         {             int j = DecodeString[i];  // char is implicitly convertible to int, so A -> 65, B -> 66 etc.             if (j >= 65 && j             {                 int k = DecodeString[i] - len; // subtract len                 if (k                 decrypted[i] = (char)k; // convert back to a character             }             else             {                 decrypted[i] = DecodeString[i]; // leave unchanged             }         }
// reverse the array         Array.Reverse(decrypted);         label2.Text = new string(decrypted); // create new string and assign to label     }

prince shils · Answer

Plz Vulpes  check my code, when i want to back my original message, some character are not correctly decode.
For example:
when i decode WONDERFULL   result returns =ONDE8F;LL which is wrong.
here is a code:
//DECODE METHOD
public string CRYPTOGRAPHY_REVERSE()
{
label1.Text = label1.Text.ToUpper();  // convert to upper case
string userString = label1.Text;
char[] decodeArray = userString.ToCharArray();
int stringLength = userString.Length;
Array.Reverse(decodeArray);
label2.Text = new string(decodeArray);
return label2.Text;
}
//DECODE BUTTON CODE
string DecodeString = CRYPTOGRAPHY_REVERSE();
int len = DecodeString.Length;
char[] encrypted = new char[len]; // create an array to hold the encrypted characters
for (int i = 0; i 65, B -> 66 etc.
if (j >= 65 && j 90) k += 26;  // wrap round if more than 90
encrypted[i] = (char)k; // convert back to a character
}
else
{
encrypted[i] = DecodeString[i]; // leave unchanged
}
}
label2.Text = new string(encrypted); // create new string and assign to label
//THANKYOU

prince shils · Answer

You are great! Thank You so much.

Vulpes · Answer

I suggest that you convert the message to all upper case, say, to make it easier to encode.
You can then use the fact that the letters A to Z have ASCII values of 65 to 90 inclusive to add 5 to them and convert back to a character. The last 5 letters V, W, X, Y and Z will need to 'wrap round' so they are mapped to A, B, C, D and E respectively.
Here's some revised code:
public string UIT_CRYPTOGRAPHY()         {             richTextBox1.Text = richTextBox1.Text.ToUpper();  // convert to upper case             string userString = richTextBox1.Text;             char[] textArray = userString.ToCharArray();             int stringLength = userString.Length;             Array.Reverse(textArray);             label1.Text = new string(textArray);
return label1.Text;         }
private void button5_Click(object sender, EventArgs e)         {             string ReverseString = UIT_CRYPTOGRAPHY();             int len = ReverseString.Length;             char[] encrypted = new char[len]; // create an array to hold the encrypted characters             for(int i = 0 ; i             {                 int j = ReverseString[i];  // char is implicitly convertible to int, so A -> 65, B -> 66 etc.                 if (j >= 65 && j                 {                     int k = ReverseString[i] + 5; // add 5                     if (k > 90) k -= 26;  // wrap round if more than 90                     encrypted[i] = (char)k; // convert back to a character                 }                 else                 {                     encrypted[i] = ReverseString[i]; // leave unchanged                 }             }             label1.Text = new string(encrypted); // create new string and assign to label         }