Okay, so I am trying to make my program take whatever your key is, and loop through each character of the key, then find the ascii code for each character code, and then loop through each character of the message, finding the ascii code of each of them, and adding the key code to the message code, doing this for each character in the key, to each character in the message. I ran into a little problem, it changes the message right after the first letter is added, and I can't figure out how to fix it, any help would be great!
Basically, all I want is to that the ascii code for the key characters and add them to the ascii code for the message characters, then convert that final code back to the new characters in the message text. Using this:
tbxMessage.Text = (AscW(Mid(tbxMessage.Text, xForMess, 1)) + AscW(vTemp))
Here is everything I've got so far:
Public Class Form1
Function fctEncryptDecrypt(pMess As String, pKey As String) As String
If Len(tbxMessage.Text) > 0 Then
Dim xForKey As Integer
Dim xForMess As Integer
Dim intKey As Integer
Dim intMessage As Integer
Dim strAsciiKeyChar As String
Dim intAsciiKeyChar As Integer
Dim strAsciiMesChar As String
Dim intAsciiMesChar As Integer
Dim vTemp As String
Dim vTempMess As String
intKey = Len(tbxKey.Text)
intMessage = Len(tbxMessage.Text)
For xForKey = 1 To intKey
strAsciiKeyChar = Mid(tbxKey.Text, xForKey, 1)
intAsciiKeyChar = AscW(strAsciiKeyChar)
vTemp = intAsciiKeyChar
For xForMess = 1 To intMessage
strAsciiMesChar = Mid(tbxMessage.Text, xForMess, 1)
intAsciiMesChar = AscW(strAsciiMesChar)
vTempMess = vTemp + intAsciiMesChar
tbxMessage.Text = (AscW(Mid(tbxMessage.Text, xForMess, 1)) + AscW(vTemp))
Next xForMess
Next xForKey
Label1.Text = vTemp
Else
MessageBox.Show("No Message Found")
End If
End Function
Private Sub btnEncrypt_Click(sender As System.Object, e As System.EventArgs) Handles btnEncrypt.Click
fctEncryptDecrypt(tbxMessage.Text, tbxKey.Text)
End Sub
End Class
tbxMessage.Text = (AscW(Mid(tbxMessage.Text, xForMess, 1)) + AscW(vTemp))
in the inner For loop is setting the value of the text box to a number.
I'd expect the use of a temporary string variable that collects
Chr((intAsciiKeyChar + intAsciiMesChar) mod 256)
I'd also expect the key to be applied one letter at a time over the message. Something like:
Dim i as Integer
Dim s as String
Dim sKey as String
Dim sMesg as String
Dim intCharacter as Integer
s = ""
For i = 1 to len(tbxMessage.Text)
sKey = Mid(tbxKey.Text, (i mod Len(tbxKey)) + 1, 1)
sMesg = Mid(tbxMessage.Text, i, 1)
intCharacter = (WAsc(sKey) + WAsc(sMesg)) mod 256
s = s & Chr(intCharacter)
Next
tbxMessage.Text = s
Related
I am developing a program where you can input a sentence and then search for a word. The program will then tell you at which positions this word occurs. I have written some code but do not know how to continue.
Module Module1
Sub Main()
Dim Sentence As String
Dim SentenceLength As Integer
Dim L As Integer = 0
Dim LotsofText As String = Console.ReadLine
Console.WriteLine("Enter your word ") : Sentence = Console.ReadLine
For L = 1 To LotsofText.Length
If (Mid(LotsofText, L, 1)) = " " Then
End If
L = L + 1
Dim TextCounter As Integer = 0
Dim MainWord As String = Sentence
Dim CountChar As String = " "
Do While InStr(MainWord, CountChar) > 0
MainWord = Mid(MainWord, 1 + InStr(MainWord, CountChar), Len(MainWord))
TextCounter = TextCounter + 1
'Text = TextCounter + 2
' Console.WriteLine(Text)
Loop
Console.WriteLine(TextCounter)
Console.Write("Press Enter to Exit")
Console.ReadLine()
End Sub
End Module
Transform this piece of code from C# to Visual Basic. match.Index will indicate the position of the given word.
var rx = new Regex("your");
foreach (Match match in rx.Matches("This is your text! This is your text!"))
{
int i = match.Index;
}
To find only words and not sub-strings (for example to ignore "cat" in "catty"):
Dim LotsofText = "catty cat"
Dim Sentence = "cat"
Dim pattern = "\b" & Regex.Escape(Sentence) & "\b"
Dim matches = Regex.Matches(LotsofText, pattern)
For Each m As Match In matches
Debug.Print(m.Index & "") ' 6
Next
If you want to find sub-strings too, you can remove the "\b" parts.
If you add this function to your code:
Public Function GetIndexes(ByVal SearchWithinThis As String, ByVal SearchForThis As String) As List(Of Integer)
Dim Result As New List(Of Integer)
Dim i As Integer = SearchWithinThis.IndexOf(SearchForThis)
While (i <> -1)
Result.Add(i)
i = SearchWithinThis.IndexOf(SearchForThis, i + 1)
End While
Return Result
End Function
And call the function in your code:
Dim Indexes as list(of Integer) = GetIndexes(LotsofText, Sentence)
Now GetIndexes will find all indexes of the word you are searching for within the sentence and put them in the list Indexes.
I am trying to write an encryption program. The problem I am facing is that I am converting the text to ascii and then adding on the offset. However when it goes past the letter 'z' I want it to warp back to 'a' and go from there.
Sub enc()
Text = TextBox1.Text
finalmessage = ""
letters = Text.ToCharArray
offset = ComboBox1.SelectedItem
For x = LBound(letters) To UBound(letters)
finalmessage = finalmessage + Chr(Asc(letters(x)) + offset)
Next
TextBox2.Text = finalmessage
End Sub
I guess to make it easy to decode afterwards, you should to it somewhat in the line of base64 encoding, first encoding everything to a normalized binary string, then encode in the range you want (since using binary, it has to be something that fits with 2^X).
To match your range, i used a baseset of 32, and a simple encoding decoding example (a bit more verbose that it should be, perhaps)
Module Module1
Dim encodeChars As String = "abcdefghijklmnopqrstuvwxyzABCDEF" ' use 32 as a base
Function Encode(text As String) As String
Dim bitEncoded As String = ""
Dim outputMessage As String = ""
For Each ch As Char In text.ToCharArray()
Dim i As Integer = Convert.ToByte(ch)
bitEncoded &= Convert.ToString(i, 2).PadLeft(8, "0"c)
Next
While bitEncoded.Length Mod 5 <> 0
bitEncoded &= "0"
End While
For position As Integer = 0 To bitEncoded.Length - 1 Step 5
Dim range As String = bitEncoded.Substring(position, 5)
Dim index As Integer = Convert.ToInt32(range, 2)
outputMessage &= encodeChars(index).ToString()
Next
Return outputMessage
End Function
Function Decode(encodedText As String) As String
Dim bitEncoded As String = ""
Dim outputMessage As String = ""
For Each ch In encodedText
Dim index As Integer = encodeChars.IndexOf(ch)
If index < 0 Then
Throw New FormatException("Invalid character in encodedText!")
End If
bitEncoded &= Convert.ToString(index, 2).PadLeft(5, "0"c)
Next
' strip the extra 0's
While bitEncoded.Length Mod 8 <> 0
bitEncoded = bitEncoded.Substring(0, bitEncoded.Length - 1)
End While
For position As Integer = 0 To bitEncoded.Length - 1 Step 8
Dim range As String = bitEncoded.Substring(position, 8)
Dim index As Integer = Convert.ToInt32(range, 2)
outputMessage &= Chr(index).ToString()
Next
Return outputMessage
End Function
Sub Main()
Dim textToEncode As String = "This is a small test, with some special characters! Just testing..."
Dim encodedText As String = Encode(textToEncode)
Dim decodedText As String = Decode(encodedText)
Console.WriteLine(textToEncode)
Console.WriteLine(encodedText)
Console.WriteLine(decodedText)
If Not String.Equals(decodedText, textToEncode) Then
Console.WriteLine("Encoding / decoding failed!")
Else
Console.WriteLine("Encoding / decoding completed succesfully!")
End If
Console.ReadLine()
End Sub
End Module
this then gives the following output?
This is a small test, with some special characters! Just testing...
krugsCzanfzsayjaonwwcBdmebAgkCBufqqhoAlunaqhgBBnmuqhgCdfmnuwcBbamnugcCtbmnAgkCtteeqeuDltoqqhizltoruwCzzofyxa
This is a small test, with some special characters! Just testing...
Encoding / decoding completed succesfully!
This question already has answers here:
How can I randomly select one of three strings?
(2 answers)
Closed 8 years ago.
I have three strings, sUpperCase, sLowerCase and sNumbers. Each have either lower characters, upper characters or numbers. I need to know how to randomly choose one of these strings. I have thought maybe by assigning them a number but I am not sure how do to this without overriding the text inside of them. Maybe even an array but I'm not sure how to do this either. Can anybody help please?
Dim sLowerCase As String = "qwertyuiopasdfghjklzxcvbnm"
Dim sUpperCase As String = "MNBVCXZLKJHGFDSAPOIUYTREWQ"
Dim sNumbers As String = "1234567890"
ANSWER:
Function GeneratePassword() As String
'
' Declare two strings as the characters which the password can be created from
Dim sLowerCase As String = "qwertyuiopasdfghjklzxcvbnm"
Dim sUpperCase As String = "MNBVCXZLKJHGFDSAPOIUYTREWQ"
Dim sNumbers As String = "1234567890"
' Create a new random.
' Random is something which gets a random set of characters from a string.
Dim random As New Random
'
' Create sPassword as a new stringbuilder
' A stringbuilder is simply a class which builds a string from multiple characters
Dim sPassword As New StringBuilder
' Not random enough
'For i As Integer = 1 To 4
' Dim idxUpper As Integer = random.Next(0, sUpperCase.Length - 1)
' sPassword.Append(sUpperCase.Substring(idxUpper, 1))
' Dim idxNumber As Integer = random.Next(0, sNumbers.Length - 1)
' sPassword.Append(sNumbers.Substring(idxNumber, 1))
' Dim idxLower As Integer = random.Next(0, sLowerCase.Length - 1)
' sPassword.Append(sLowerCase.Substring(idxLower, 1))
'Next
' Random select Upper, lower or numeric
' Check for a max number of this(three if's to check for which one it was, might need or in if)
' If yes randomly select another one
' If no get random char from that type
' Add to password
' Is the password complete?
' If yes return password, if not repeat
Dim iCountUpper As Integer = 0
Dim iCountLower As Integer = 0
Dim iCountNumber As Integer = 0
Do Until sPassword.Length = 10
'Needed help for this bit
Dim x = New Random(Now.GetHashCode)
Dim y = {"sLowerCase", "sUpperCase", "sNumbers"}
Dim z = y(x.Next(0, y.Length))
If z.Contains("sLowerCase") And iCountUpper < 4 Then
Dim idxUpper As Integer = random.Next(0, sUpperCase.Length - 1)
sPassword.Append(sUpperCase.Substring(idxUpper, 1))
iCountUpper = iCountUpper + 1
ElseIf z.Contains("sUpperCase") And iCountLower < 4 Then
Dim idxLower As Integer = random.Next(0, sLowerCase.Length - 1)
sPassword.Append(sLowerCase.Substring(idxLower, 1))
iCountLower = iCountLower + 1
ElseIf z.Contains("sNumbers") And iCountNumber < 2 Then
Dim idxNumber As Integer = random.Next(0, sNumbers.Length - 1)
sPassword.Append(sNumbers.Substring(idxNumber, 1))
iCountNumber = iCountNumber + 1
Else
End If
Loop
'
' Return the password as a string
Return sPassword.ToString
End Function
You could do something like this:
Dim sLowerCase As String = "qwertyuiopasdfghjklzxcvbnm"
Dim sUpperCase As String = "MNBVCXZLKJHGFDSAPOIUYTREWQ"
Dim sNumbers As String = "1234567890"
Dim x = New Random(Now.GetHashCode)
Dim y = {sLowerCase, sUpperCase, sNumbers}
Dim z = y(x.Next(0, y.Length))
Debug.Print(z)
Dim strings = {"qwertyuiopasdfghjklzxcvbnm", "MNBVCXZLKJHGFDSAPOIUYTREWQ", "1234567890"}
Dim selected As String
Dim Generator As System.Random = New System.Random()
selected = strings(Generator.Next(0, strings.GetUpperBound(0)))
Create an array with your strings:
Dim array As String() = New String() {sLowerCase, sUpperCase, sNumbers}
Use Random class to generate random number between 0 and the array lenght:
Dim random As Random = New Random(DateTime.Now.Ticks)
Dim randomChoose As String = array(random.Next(0, array.Length - 1))
Select a random char:
Dim ch As Char = randomChoose(random.Next(0, randomChoose.Length - 1))
I currently have a file with 1 million characters.. the file is 1 MB in size. I am trying to parse data with this old function that still works but very slow.
start0end
start1end
start2end
start3end
start4end
start5end
start6end
the code, takes about 5 painful minutes to process the whole data.
any pointers and suggestions are appreciated.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim sFinal = ""
Dim strData = textbox.Text
Dim strFirst = "start"
Dim strSec = "end"
Dim strID As String, Pos1 As Long, Pos2 As Long, strCur As String = ""
Do While InStr(strData, strFirst) > 0
Pos1 = InStr(strData, strFirst)
strID = Mid(strData, Pos1 + Len(strFirst))
Pos2 = InStr(strID, strSec)
If Pos2 > 0 Then
strID = Microsoft.VisualBasic.Left(strID, Pos2 - 1)
End If
If strID <> strCur Then
strCur = strID
sFinal += strID & ","
End If
strData = Mid(strData, Pos1 + Len(strFirst) + 3 + Len(strID))
Loop
End Sub
The reason that is so slow is because you keep destroying and recreating a 1 MB string over and over. Strings are immutable, so strData = Mid(strData... creates a new string and copies the remaining of the 1 MB string data to a new strData variable over and over and over. Interestingly, even VB6 allowed for a progressive index.
I would have processed the disk file LINE BY LINE and plucked out the info as it was read (see streamreader.ReadLine) to avoid working with a 1MB string. Pretty much the same method could be used there.
' 1 MB textbox data (!?)
Dim sData As String = TextBox1.Text
' start/stop - probably fake
Dim sStart As String = "start"
Dim sStop As String = "end"
' result
Dim sbResult As New StringBuilder
' progressive index
Dim nNDX As Integer = 0
' shortcut at least as far as typing and readability
Dim MagicNumber As Integer = sStart.Length
' NEXT index of start/stop after nNDX
Dim i As Integer = 0
Dim j As Integer = 0
' loop as long as string remains
Do While (nNDX < sData.Length) AndAlso (i >= 0)
i = sData.IndexOf(sStart, nNDX) ' start index
j = sData.IndexOf(sStop, i) ' stop index
' Extract and append bracketed substring
sbResult.Append(sData.Substring(i + MagicNumber, j - (i + MagicNumber)))
' add a cute comma
sbResult.Append(",")
nNDX = j ' where we start next time
i = sData.IndexOf(sStart, nNDX)
Loop
' remove last comma
sbResult.Remove(sbResult.ToString.Length - 1, 1)
' show my work
Console.WriteLine(sbResult.ToString)
EDIT: Small mod for the ad hoc test data
well i know that there are a lot of these threads but im new to vb.net yet i cant edit the sources given to make what i really want
so i want a function that will generate random strings which will contain from 15-32 characters each and each of them will have the following chars ( not all at the same string but some of them ) :
A-Z
a-z
0-9
here is my code so far
Functon RandomString()
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
Dim r As New Random
Dim sb As New StringBuilder
For i As Integer = 1 To 8
Dim idx As Integer = r.Next(0, 35)
sb.Append(s.Substring(idx, 1))
Next
return sb.ToString()
End Function
Change the string to include the a-z characters:
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Change the loop to create a random number of characters:
Dim cnt As Integer = r.Next(15, 33)
For i As Integer = 1 To cnt
Note that the upper boundary in the Next method is exclusive, so Next(15, 33) gives you a value that can range from 15 to 32.
Use the length of the string to pick a character from it:
Dim idx As Integer = r.Next(0, s.Length)
As you are going to create random strings, and not a single random string, you should not create the random number generator inside the function. If you call the function twice too close in time, you would end up with the same random string, as the random generator is seeded using the system clock. So, you should send the random generator in to the function:
Function RandomString(r As Random)
So, all in all:
Function RandomString(r As Random)
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Dim sb As New StringBuilder
Dim cnt As Integer = r.Next(15, 33)
For i As Integer = 1 To cnt
Dim idx As Integer = r.Next(0, s.Length)
sb.Append(s.Substring(idx, 1))
Next
return sb.ToString()
End Function
Usage example:
Dim r As New Random
Dim strings As New List<string>()
For i As Integer = 1 To 10
strings.Add(RandomString(r))
Next
Try something like this:-
stringToReturn&= Guid.NewGuid.ToString().replace("-","")
You can also check this:-
Sub Main()
Dim KeyGen As RandomKeyGenerator
Dim NumKeys As Integer
Dim i_Keys As Integer
Dim RandomKey As String
''' MODIFY THIS TO GET MORE KEYS - LAITH - 27/07/2005 22:48:30 -
NumKeys = 20
KeyGen = New RandomKeyGenerator
KeyGen.KeyLetters = "abcdefghijklmnopqrstuvwxyz"
KeyGen.KeyNumbers = "0123456789"
KeyGen.KeyChars = 12
For i_Keys = 1 To NumKeys
RandomKey = KeyGen.Generate()
Console.WriteLine(RandomKey)
Next
Console.WriteLine("Press any key to exit...")
Console.Read()
End Sub
Using your function as a guide, I modified it to:
Randomize the length (between minChar & maxCharacters)
Randomize the string produced each time (by using the static Random)
Code:
Function RandomString(minCharacters As Integer, maxCharacters As Integer)
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
Static r As New Random
Dim chactersInString As Integer = r.Next(minCharacters, maxCharacters)
Dim sb As New StringBuilder
For i As Integer = 1 To chactersInString
Dim idx As Integer = r.Next(0, s.Length)
sb.Append(s.Substring(idx, 1))
Next
Return sb.ToString()
End Function
Try this out:
Private Function RandomString(ByRef Length As String) As String
Dim str As String = Nothing
Dim rnd As New Random
For i As Integer = 0 To Length
Dim chrInt As Integer = 0
Do
chrInt = rnd.Next(30, 122)
If (chrInt >= 48 And chrInt <= 57) Or (chrInt >= 65 And chrInt <= 90) Or (chrInt >= 97 And chrInt <= 122) Then
Exit Do
End If
Loop
str &= Chr(chrInt)
Next
Return str
End Function
You need to change the line For i As Integer = 1 To 8 to For i As Integer = 1 To ? where ? is the number of characters long the string should be. This changes the number of times it repeats the code below so more characters are appended to the string.
Dim idx As Integer = r.Next(0, 35)
sb.Append(s.Substring(idx, 1))
My $.02
Dim prng As New Random
Const minCH As Integer = 15 'minimum chars in random string
Const maxCH As Integer = 35 'maximum chars in random string
'valid chars in random string
Const randCH As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Private Function RandomString() As String
Dim sb As New System.Text.StringBuilder
For i As Integer = 1 To prng.Next(minCH, maxCH + 1)
sb.Append(randCH.Substring(prng.Next(0, randCH.Length), 1))
Next
Return sb.ToString()
End Function
please note that the
r.Next(0, 35)
tend to hang and show the same result Not sure whay; better to use
CInt(Math.Ceiling(Rnd() * N)) + 1
see it here Random integer in VB.NET
I beefed up Nathan Koop's function for my own needs, and thought I'd share.
I added:
Ability to add Prepended and Appended text to the random string
Ability to choose the casing of the allowed characters (letters)
Ability to choose to include/exclude numbers to the allowed characters
NOTE: If strictly looking for an exact length string while also adding pre/appended strings you'll need to deal with that; I left out any logic to handle that.
Example Usages:
' Straight call for a random string of 20 characters
' All Caps + Numbers
String_Random(20, 20, String.Empty, String.Empty, 1, True)
' Call for a 30 char string with prepended string
' Lowercase, no numbers
String_Random(30, 30, "Hey_Now_", String.Empty, 2, False)
' Call for a 15 char string with appended string
' Case insensitive + Numbers
String_Random(15, 15, String.Empty, "_howdy", 3, True)
.
Public Function String_Random(
intMinLength As Integer,
intMaxLength As Integer,
strPrepend As String,
strAppend As String,
intCase As Integer,
bIncludeDigits As Boolean) As String
' Allowed characters variable
Dim s As String = String.Empty
' Set the variable to user's choice of allowed characters
Select Case intCase
Case 1
' Uppercase
s = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Case 2
' Lowercase
s = "abcdefghijklmnopqrstuvwxyz"
Case Else
' Case Insensitive + Numbers
s = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
End Select
' Add numbers to the allowed characters if user chose so
If bIncludeDigits = True Then s &= "0123456789"
Static r As New Random
Dim chactersInString As Integer = r.Next(intMinLength, intMaxLength)
Dim sb As New StringBuilder
' Add the prepend string if one was passed
If String.IsNullOrEmpty(strPrepend) = False Then sb.Append(strPrepend)
For i As Integer = 1 To chactersInString
Dim idx As Integer = r.Next(0, s.Length)
sb.Append(s.Substring(idx, 1))
Next
' Add the append string if one was passed
If String.IsNullOrEmpty(strAppend) = False Then sb.Append(strAppend)
Return sb.ToString()
End Function