I am writing a Ceasaer Function that takes a string and runs it through a variant of the Ceasear cipher, and returns the encoded text. For some reason I am getting an Index Out Of Range error on an Array declared with no specific bounds. Why am I getting this exception, and how do I fix it?
VB.NET Code:
Public Shared Function Ceaser(ByVal str As String) As String
Dim r As String = ""
Dim ints() As Integer = {}
Dim codeints As Integer() = {}
Dim codedints As Integer() = {}
Dim ciphertext As String = ""
For i As Integer = 0 To str.Length - 1
Dim currentch As Integer = Map(str(i))
ints(i) = currentch 'Where exception is happening
Next
Dim primes As Integer() = PrimeNums(ints.Length)
For i As Integer = 0 To primes.Length - 1
codeints(i) = ints(i) + primes(i) - 3
Next
For i As Integer = 0 To codeints.Length - 1
Dim currentnum As Integer = codeints(i) Mod 27
codedints(i) = currentnum
Next
For i As Integer = 0 To codedints.Length - 1
Dim letter As String = rMap(codeints(i))
ciphertext += letter
Next
Return ciphertext
End Function
You have to specify the array bounds before you can acces its elements:
Dim ints As Integer(str.length-1)
will instantiate the array with n elements where n = length of string str.
(Take care: VB .NET array lengths are zero-based, so an array with 1 element is instantiated with array(0)).
You have to adopt the other arrays accordingly.
Related
I have to store numbers contained in a string into arrays in a special way.
The string contains comma and hyphen.
The comma-separated numbers should be stored individually
Numbers separated by a hyphen should be stored as a range of values.
For example, my string is:
Reg. No 556002,556010-556013,556039 Cancelled
The array should store the numbers as:
(0) 556002 - Single
(1) 556010 ---------|
(2) 556011 Range of
(3) 556012 values
(4) 556013 ---------|
(5) 556039 - Single
I tried the following code:
Dim i, str
Dim array() As Char = str.ToCharArray()
Dim rnoarray() As Integer = New Integer() {}
Dim rno = ""
Dim nosta As Boolean
Dim j = 0
str = "Reg. No 556002,556010-556013,556039 Cancelled"
nosta = False
ReDim rnoarray(Len(str) + 2)
For i = 0 To Len(str)-1
If IsNumeric(array(i)) Then
rno = rno & array(i)
nosta = True
Else
If nosta = True Then
rnoarray(j) = Val(rno)
j = j + 1
nosta = False
rno = ""
End If
End If
Next
For x = 0 To j - 1
MessageBox.Show(rnoarray(x))
Next
But the result only includes four numbers:
556002
556010
556013
556039
Some steps to consider:
Extract the numbers from the input string, preserving the hyphen when present
Verify whether one of the parts contains a hyphen:
In this case, Split() the string into two parts
Convert to Integer the two parts
Take the minimum and the maximum values
Create a range of numbers between the minimum and maximum values
Add the range of numbers to a List(Of Integer)
Convert strings that do not contain a hyphen to Integer
Add the converted numbers to a List(Of Integer)
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text.RegularExpressions
Dim input = "Reg. No 556002,556010-556013,556039 Cancelled"
Dim numbers As New List(Of Integer)
Dim matches = Regex.Matches(input, "\d+-*\d*").OfType(Of Match)
For Each m As Match In matches
If m.Value.Contains("-") Then
Dim parts = m.Value.Split("-"c).Select(Function(s) Integer.Parse(s)).ToArray()
Dim nStart As Integer = Math.Min(parts(0), parts(1))
Dim nEnd As Integer = Math.Max(parts(0), parts(1))
numbers.AddRange(Enumerable.Range(nStart, nEnd - nStart + 1))
Else
numbers.Add(Integer.Parse(m.Value))
End If
Next
Without Regular Expression (assuming the input string format presented here matches the original):
For Each part As String In input.Split(","c)
If part.Contains("-") Then
Dim nValues = part.Split("-"c).Select(Function(s) Integer.Parse(s)).ToArray()
Dim nStart As Integer = Math.Min(nValues(0), nValues(1))
Dim nEnd As Integer = Math.Max(nValues(0), nValues(1))
numbers.AddRange(Enumerable.Range(nStart, nEnd - nStart + 1))
Else
Dim sValue = String.Concat(part.Where(Function(c) Char.IsDigit(c)))
numbers.Add(Integer.Parse(sValue))
End If
Next
I have a number (say 5) which I would first like to convert to binary (101) and then split into an array of bits {1,0,1} or Booleans {True,False,True} in VBA
Is there a way to do this without looping?
I can convert to Binary without looping in my code with the worksheet formula as follows
myBinaryNum = [DEC2BIN(myDecInteger,[places])]
But I've been told that worksheet functions are very inefficient, and this one is particularly limited.
I'm not sure how to split into an array without looping through the digits with MID. Is there anything like strConv for numbers?
You could first convert the value to a "01" string with WorksheetFunction.Dec2Bin.
Then replace each "0","1" with the code 0 or 1 and cast the result to a Byte array :
Public Function ToBitArray(ByVal value As Long) As Byte()
Dim str As String
str = WorksheetFunction.Dec2Bin(value) ' "101"
str = Replace(Replace(str, "0", ChrW(0)), "1", ChrW(1)) ' "\u0001\u0000\u0001"
ToBitArray = StrConv(str, vbFromUnicode) ' [1, 0, 1]
End Function
But Dec2Bin is limited to 511 and working with strings is rather expensive. So if your goal is to get the best performance, then you should use a loop to read each bit:
Public Function ToBitArray(ByVal value As Long) As Byte()
Dim arr(0 To 31) As Byte, i As Long
i = 32&
Do While value
i = i - 1
arr(i) = value And 1
value = value \ 2
Loop
ToBitArray = MidB(arr, i + 1) ' trim leading zeros
End Function
I found this neat code on another question here at SO. Basically, you can be sure your string is ASCII due to the fact it's 1's and 0's.
What you do is you use
Dim my_string As String
my_string = CStr("your binary number")
To turn your binary number into a string
And then
Dim buff() As String
buff = Split(StrConv(my_string, vbUnicode), Chr$(0))
ReDim Preserve buff(UBound(buff) - 1
To split that string into an array where buff is your array
I think you've probably got everything you need above from other answers, but if you want a simple function that takes the decimal and returns the array..
Function dec_to_binary_array(decNum As Integer)
Dim arr() As String, NumAsString As String
NumAsString = Application.Dec2Bin(decNum)
arr = Split(StrConv(NumAsString, vbUnicode), vbNullChar)
ReDim Preserve arr(UBound(arr) - 1)
dec_to_binary_array = arr
End Function
Invoking Application.Dec2Bin(n) isn't realy expensive, it only costs a late bound call. Use the function below to transform any integer into an arrays of bits:
Function Bits(n as long)
Dim s As String: s = Application.Dec2Bin(n)
Dim ar: ar = Split(StrConv(s, vbUnicode), vbNullChar)
Bits = ar
End Function
p.s.: s will only contain 0 and 1 which are ASCII characters, so the split technique is perfectly valid.
Function d2bin(dec As Integer, bits As Integer) As Integer()
Dim maxVal As Integer
maxVal = 2 ^ (bits)-1
If dec > maxVal Then Exit Function
Dim i As Integer
Dim result() As Integer
ReDim result(0 To bits - 1)
For i = bits - 1 To 0 Step -1
result(bits - i - 1) = -(dec > (2 ^ (i) - 1))
If result(bits - i - 1) Then dec = dec - (2 ^ i)
Next i
d2bin = result
End Function
Please check this code if this is what you need:
You can replace the the digit 5 by any cell value reference, this is just and example:
Sub dectobinary()
Dim BinaryString As String
BinaryString = "5"
tempval = Dec2Bin(BinaryString)
MsgBox tempval
End Sub
Function Dec2Bin(ByVal DecimalIn As Variant) As String
Dec2Bin = ""
DecimalIn = Int(CDec(DecimalIn))
Do While DecimalIn <> 0
Dec2BinTemp = Format$(DecimalIn - 2 * Int(DecimalIn / 2))
If Dec2BinTemp = "1" Then
Dec2Bin = "True" & "," & Dec2Bin
Else
Dec2Bin = "False" & "," & Dec2Bin
End If
DecimalIn = Int(DecimalIn / 2)
Loop
End Function
Just change lngNumber value to your desired number
Public Sub sChangeNumberToBinaryArray()
Dim strBinaryNumber As String
Dim strBinaryArray() As String
Dim lngNumber As Long
lngNumber = 5
strBinaryNumber = DecToBin(lngNumber)
strBinaryArray() = Split(strBinaryNumber, "|")
End Sub
Function DecToBin(ByVal varDecimalIn As Variant) As String
Dim lngCounter As Long
DecToBin = ""
varDecimalIn = Int(CDec(varDecimalIn))
lngCounter = 1
Do While varDecimalIn <> 0
If lngCounter = 1 Then
DecToBin = Format$(varDecimalIn - 2 * Int(varDecimalIn / 2)) & DecToBin
lngCounter = lngCounter + 1
Else
DecToBin = Format$(varDecimalIn - 2 * Int(varDecimalIn / 2)) & "|" & DecToBin
lngCounter = lngCounter + 1
End If
varDecimalIn = Int(varDecimalIn / 2)
Loop
End Function
I need an array indexed with strings, like this:
Dim Array ("A") as integer' <-- I need an array like this
Dim StringArray() as string = {"A","B","C","A","A","B","D"}
For each Letter in StringArray
Array(Letter) += 1
next
Results I wanted but not worked:
Array(A) = 3
Array(B) = 2
Array(C) = 1
Array(D) = 1
I, also tried List's, not working:
Dim Array As New List(Of Object)
Dim StringArray() as string = {"A","B","C","A","A","B","D"}
For each Letter in StringArray
Array(Letter) += 1
next
Is there a way count strings this way in VB .Net?
You can use a Dictionary(Of TKey, TValue) where your letters are the keys, and the values will store your totals:
Dim dict = New Dictionary(Of Char, Integer)
dict.Add("A"c, 0)
dict.Add("B"c, 0)
dict.Add("C"c, 0)
dict.Add("D"c, 0)
Dim stringArray() As Char = {"A"c, "B"c, "C"c, "A"c, "A"c, "B"c, "D"c}
For Each letter In stringArray
dict.Item(letter) += 1
Next
I'm searching a way to check if an array contains all the elements of another array.
This is the situation: I have two bytes arrays Bytes(): one contains the bytes of a file, and another contains the bytes to compare.
For example, if the file contains these bytes: 4D 5A 90 00 03 and the string to compare is 00 03, I want the function to return true. Else it will obviously return false. So, all bytes in the string to compare must be present in the file too.
I've already searched on the web for this. Tried the old good Contains() function, but for arrays it works only to compare a single byte. You know, one byte only is too little to identify a file!
If possible, I'd like to do this as fast as possible.
I'm working in VB.NET WinForms, VS 2013, .NET 4.5.1
Thanks in advance,
FWhite
EDIT:
Now I have a List(Of Bytes()) like this:
00 25 85 69
00 41 52
00 78 96 32
These are three Bytes() arrays. How do I check if my file bytes array contains all of these values (the file must contains 00 25 85 69, 00 41 52 and 00 78 96 32? I've tried with this code, but it doesn't work:
Dim BytesToCompare As List(Of Byte()) = StringToByteArray(S.Split(":")(3))
For Each B As Byte() In BytesToCompare
If FileBytes.All(Function(c) B.Contains(c)) Then
'Contains
TempResults.Add("T")
Else
TempResults.Add("F")
End If
Next
If CountResults(TempResults) Then
Return S
Exit For
End If
The code in CountResults is this:
Public Function CountResults(Input As List(Of String)) As Boolean
Dim TrueCount As Integer = 0
Dim FalseCount As Integer = 0
Dim TotalCount As Integer = Input.Count
For Each S In Input
If S = "T" Then
TrueCount = TrueCount + 1
ElseIf S = "F" Then
FalseCount = FalseCount + 1
End If
Next
If TrueCount = TotalCount Then
Return True
ElseIf FalseCount > TrueCount Then
Return False
End If
End Function
Tell me if you didn't understand and I'll try to better explain.
Thank you,
FWhite
I was thinking that maybe something other than the brute-force method would work and discovered the Boyer-Moore search algorithm. Shamelessly translating the C and Java code found at Boyer–Moore string search algorithm into VB.NET, I arrived at
Public Class BoyerMooreSearch
' from C and Java code at http://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string_search_algorithm
Private Shared Function SuffixLength(needle As Byte(), p As Integer) As Integer
Dim len As Integer = 0
Dim j = needle.Length - 1
Dim i = 0
While i >= 0 AndAlso needle(i) = needle(j)
i -= 1
j -= 1
len += 1
End While
Return len
End Function
Private Shared Function GetOffsetTable(needle As Byte()) As Integer()
Dim table(needle.Length - 1) As Integer
Dim lastPrefixPosition = needle.Length
For i = needle.Length - 1 To 0 Step -1
If Isprefix(needle, i + 1) Then
lastPrefixPosition = i + 1
End If
table(needle.Length - 1 - i) = lastPrefixPosition - i + needle.Length - 1
Next
For i = 0 To needle.Length - 2
Dim slen = SuffixLength(needle, i)
table(slen) = needle.Length - 1 - i + slen
Next
Return table
End Function
Private Shared Function Isprefix(needle As Byte(), p As Integer) As Boolean
Dim j = 0
For i = p To needle.Length - 1
If needle(i) <> needle(j) Then
Return False
End If
j += 1
Next
Return True
End Function
Private Shared Function GetCharTable(needle As Byte()) As Integer()
Const ALPHABET_SIZE As Integer = 256
Dim table(ALPHABET_SIZE - 1) As Integer
For i = 0 To table.Length - 1
table(i) = needle.Length
Next
For i = 0 To needle.Length - 2
table(needle(i)) = needle.Length - 1 - i
Next
Return table
End Function
Shared Function IndexOf(haystack As Byte(), needle As Byte()) As Integer
If needle.Length = 0 Then
Return 0
End If
Dim charTable = GetCharTable(needle)
Dim offsetTable = GetOffsetTable(needle)
Dim i = needle.Length - 1
While i < haystack.Length
Dim j = needle.Length - 1
While j >= 0 AndAlso haystack(i) = needle(j)
i -= 1
j -= 1
End While
If j < 0 Then
Return i + 1
End If
i += Math.Max(offsetTable(needle.Length - 1 - j), charTable(haystack(i)))
End While
Return -1
End Function
End Class
And to test it (suspecting that the LINQ code presented by #OneFineDay would demolish it for performance):
Imports System.IO
Imports System.Text
Module Module1
Dim bytesToCheck As List(Of Byte())
Dim rand As New Random
Function GetTestByteArrays() As List(Of Byte())
Dim testBytes As New List(Of Byte())
' N.B. adjust the numbers used in CreateTestFile according to the quantity (e.g. 10) of testData used
For i = 1 To 10
testBytes.Add(Encoding.ASCII.GetBytes("ABCDEFgfdhgf" & i.ToString() & "sdfgjdfjFGH"))
Next
Return testBytes
End Function
Sub CreateTestFile(f As String)
' Make a 4MB file of test data
' write a load of bytes which are not going to be in the
' judiciously chosen data to search for...
Using fs As New FileStream(f, FileMode.Create, FileAccess.Write)
For i = 0 To 2 ^ 22 - 1
fs.WriteByte(CByte(rand.Next(128, 256)))
Next
End Using
' ... and put the known data into the test data
Using fs As New FileStream(f, FileMode.Open)
For i = 0 To bytesToCheck.Count - 1
fs.Position = CLng(i * 2 ^ 18)
fs.Write(bytesToCheck(i), 0, bytesToCheck(i).Length)
Next
End Using
End Sub
Sub Main()
' the byte sequences to be searched for
bytesToCheckFor = GetTestByteArrays()
' Make a test file so that the data can be inspected
Dim testFileName As String = "C:\temp\testbytes.dat"
CreateTestFile(testFileName)
Dim fileData = File.ReadAllBytes(testFileName)
Dim sw As New Stopwatch
Dim containsP As Boolean = True
sw.Reset()
sw.Start()
For i = 0 To bytesToCheckFor.Count - 1
If BoyerMooreSearch.IndexOf(fileData, bytesToCheckFor(i)) = -1 Then
containsP = False
Exit For
End If
Next
sw.Stop()
Console.WriteLine("Boyer-Moore: {0} in {1}", containsP, sw.ElapsedTicks)
sw.Reset()
sw.Start()
Dim temp As New List(Of Byte)
Array.ForEach(bytesToCheckFor.ToArray, Sub(byteArray) Array.ForEach(byteArray, Sub(_byte) temp.Add(_byte)))
Dim result = fileData.All(Function(_byte) temp.Contains(_byte))
sw.Stop()
Console.WriteLine("LINQ: {0} in {1}", result, sw.ElapsedTicks)
Console.ReadLine()
End Sub
End Module
Now, I know that the byte sequences to match are in the test file (I confirmed that by using a hex editor to search for them) and, assuming (oh dear!) I am using the other method correctly, the latter doesn't work whereas mine does:
Boyer-Moore: True in 23913
LINQ: False in 3224
I did also test the first code example by OneFineDay for searching for small vs large patterns to match, and for less than seven or eight bytes that code was faster than Boyer-Moore. So, if you would care to test it for the size of data you're searching in and the size of the patterns you're looking for, Boyer-Moore might be a better fit to your "If possible, I'd like to do this as fast as possible."
EDIT
Further to the OP's uncertainty as to whether or not my suggested method works, here is a test with very small sample data:
Sub Test()
bytesToCheckFor = New List(Of Byte())
bytesToCheckFor.Add({0, 1}) ' the data to search for
bytesToCheckFor.Add({1, 2})
bytesToCheckFor.Add({0, 2})
Dim fileData As Byte() = {0, 1, 2} ' the file data
' METHOD 1: Boyer-Moore
Dim containsP As Boolean = True
For i = 0 To bytesToCheckFor.Count - 1
If BoyerMooreSearch.IndexOf(fileData, bytesToCheckFor(i)) = -1 Then
containsP = False
Exit For
End If
Next
Console.WriteLine("Boyer-Moore: {0}", containsP)
' METHOD 2: LINQ
Dim temp As New List(Of Byte)
Array.ForEach(bytesToCheckFor.ToArray, Sub(byteArray) Array.ForEach(byteArray, Sub(_byte) temp.Add(_byte)))
Dim result = fileData.All(Function(_byte) temp.Contains(_byte))
Console.WriteLine("LINQ: {0}", result)
Console.ReadLine()
End Sub
Outputs:
Boyer-Moore: False
LINQ: True
Also, I renamed the variables in my original Main() method to hopefully make them more meaningful.
You can use the All function to check for that. It returns a Boolean.
Dim orgByteArray() As Byte = {CByte(1), CByte(2), CByte(3)}
Dim testByteArray() As Byte = {CByte(1), CByte(2)}
Dim result = orgByteArray.All(Function(b) testByteArray.Contains(b))
'output for this case returns False
For comparing a List(Of Byte()) to a Byte() where the Byte() is the complte list of all sub arrays in the List(Of byte()).
Dim filebytes() As Byte = {CByte(1), CByte(2), CByte(3), CByte(3), CByte(4), CByte(5), CByte(6), CByte(7), CByte(8)}
Dim bytesToCheck As New List(Of Byte())
bytesToCheck.Add(New Byte() {CByte(1), CByte(2), CByte(3)})
bytesToCheck.Add(New Byte() {CByte(3), CByte(4), CByte(5)})
bytesToCheck.Add(New Byte() {CByte(6), CByte(7), CByte(8)})
Dim temp As New List(Of Byte)
Array.ForEach(bytesToCheck.ToArray, Sub(byteArray) Array.ForEach(byteArray, Sub(_byte) temp.Add(_byte)))
Dim result = filebytes.All(Function(_byte) temp.Contains(_byte))
'output = True
I don't understand why for each loop in vba doesn't return the good number of element when i use dynamic array.
For exemple, my array size is 4, and i have 5 iteration in for each loop ...
Public Sub test()
Dim t_direction() As String
Dim t_nextDirection() As String
Dim myDirection As Variant
Dim test As Integer
Var = 0
ReDim t_direction(4)
t_direction(0) = "N"
t_direction(1) = "S"
t_direction(2) = "E"
t_direction(3) = "W"
t_nextDirection = randomizeArray(t_direction)
For Each myDirection In t_nextDirection
Var = Var + 1
Next myDirection
MsgBox (UBound(t_nextDirection))
MsgBox (Var)
End Sub
Public Function randomizeArray(ByVal t_array As Variant) As String()
Dim i As Integer
Dim j As Integer
Dim tmp As String
Dim numItems As Integer
numItems = UBound(t_array) - 1
' Randomize the array.
For i = 0 To numItems
' Pick a random entry.
j = Rand(0, numItems)
' Swap the numbers.
tmp = t_array(i)
t_array(i) = t_array(j)
t_array(j) = tmp
Next i
'MsgBox (UBound(t_array))
randomizeArray = t_array
End Function
Public Function Rand(ByVal Low As Long, _
ByVal High As Long) As Integer
Rand = Int((High - Low + 1) * Rnd) + Low
End Function
At the moment you are creating a 5 element array with
ReDim t_direction(4)
as the first element occurs as t_direction(0)
You should either
create a 4 element array ReDim t_direction(3) (ie 0 to 3) and then use numItems consistent with that, or
create a 4 element array ReDim t_direction with a base of 1 (ie 1 to 4) and then use numItems consistent with that (ie numItems = UBound(t_array)). The Option Base 1 below forces the first element to be 1 (which is then ensured anyow by using ReDim t_direction(1 To 4)
The code below uses the later approach. It returns 4 and 4 rather than your current 4 and 5
Option Base 1
Public Sub test()
Dim t_direction() As String
Dim t_nextDirection() As String
Dim myDirection As Variant
Dim test As Integer
Var = 0
ReDim t_direction(1 To 4)
t_direction(1) = "N"
t_direction(2) = "S"
t_direction(3) = "E"
t_direction(4) = "W"
t_nextDirection = randomizeArray(t_direction)
For Each myDirection In t_nextDirection
Var = Var + 1
Next myDirection
MsgBox (UBound(t_nextDirection))
MsgBox (Var)
End Sub
Public Function randomizeArray(ByVal t_array As Variant) As String()
Dim i As Integer
Dim j As Integer
Dim tmp As String
Dim numItems As Integer
numItems = UBound(t_array)
' Randomize the array.
For i = 1 To numItems
' Pick a random entry.
j = Rand(1, numItems)
' Swap the numbers.
tmp = t_array(i)
t_array(i) = t_array(j)
t_array(j) = tmp
Next i
'MsgBox (UBound(t_array))
randomizeArray = t_array
End Function
Public Function Rand(ByVal Low As Long, _
ByVal High As Long) As Integer
Rand = Int((High - Low + 1) * Rnd) + Low
End Function
ReDim t_direction(4) actually declares t_direction as 0 To 4
Its better to be explicit:
ReDim t_direction(0 To 3)
In the absence of a specified lower bound (using the To clause), then the default lower bound is used.
This default can be set to 0 or 1 by using Option Base {0|1} at module level.
In the absence of Option Base then the default default is 0
Notes:
In VBA you are not limited to 0 or 1 as the lower bound, you can use any value you want.
To iterate over an array use
For i = LBound(arr) To UBound(arr)
To calculate the number of items in an array use
numItems = UBound(arr) - LBound(arr) + 1
This way you are not making any assumptions on what the lower bound is