Sorry for my poor English.
I just curious if does the Random alphanumeric is very unique even i have a millions of data? Because I develop a software that I want every data have a unique Alphanumeric.
By the way, how many sets of random does this code make?
Dim s As String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
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
random.Text = sb.ToString()
Related
enter image description hereWrite a program to display 1000 8-character random user IDs in a text box after you click a button. Make sure the program verifies that none of the IDs are identical. Each userid should include a mixture of alphabetic characters and numbers.
What I have so far, which could be enough to get by as a random ID generator alone, but it does not loop 1000 times to be displayed in the label, and doesn't check for repeated ID's.
Public Class Form1
Private Sub btnGenerateRandomID_Click(sender As Object, e As EventArgs) Handles btnGenerateRandomID.Click
Dim rand As New Random
Dim char1 As String
Dim char2 As String
Dim char3 As String
Dim char4 As String
Dim char5 As String
Dim char6 As String
Dim char7 As String
Dim char8 As String
char1 = ChrW(rand.Next(Asc("A"), Asc("Z") + 1))
char2 = ChrW(rand.Next(Asc("A"), Asc("Z") + 1))
char3 = ChrW(rand.Next(Asc("A"), Asc("Z") + 1))
char4 = ChrW(rand.Next(Asc("A"), Asc("Z") + 1))
char5 = rand.Next(0, 9)
char6 = rand.Next(0, 9)
char7 = rand.Next(0, 9)
char8 = rand.Next(0, 9)
lblRandomId.Text = char1 + char2 + char3 + char4 + char5 + char6 + char7 + char8
End Sub
End Class
Thanks.
EDIT:
Public Class Form1
'Write a program to display 1000 8-character random user IDs in a text
'box after you click a button. Make sure the program verifies that none Of the IDs are identical.
'Each userid should include a mixture Of alphabetic characters And numbers.
Private Sub btnGenerateRandomID_Click(sender As Object, e As EventArgs) Handles btnGenerateRandomID.Click
Dim strChar As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Dim rand As New Random
Dim strID As String = ""
For count_ids As Integer = 0 To 999
For count_chars As Integer = 0 To 7
strID += strChar(rand.Next(0, 62))
Next count_chars
lblRandomId.Text = strID
Next
End Sub
End Class
Here is the actual question "Q. Write a program to display 1000 8-character random user IDs in a text box after you click a button. Make sure the program verifies that none of the IDs are identical. Each userid should include a mixture of alphabetic characters and numbers.
Explain your program in your essay, with screenshots. Include a paragraph on the random number generator used in Visual Basic, and answer the question: how should the random number generator be best seeded?"
First of all, Welcome to StackOverflow,
From what i understand from your post you want to generate 1000 8 Character long Unique ID's
First of all we declare our variables
Dim Characters As String = "AZERTYUIOPQSDFGHJKLMWXCVBN0123456789" 'Declare All Characters on one string
Dim IDsList As New List(Of String) With {.Capacity = 1000} 'You can limit the capacity to 1000
Dim Id As String = ""
Dim Rand As New Random
Now we begin to genearte ID's and add them to IDsList using a nested loop
For i As Integer = 0 To 999 'This is a Zero Based Index so 999 is actually 1000
For _i As Integer = 0 To 7 'This also means 7 is 8
Id += Characters(Rand.Next(0, 36))
Next
IDsList.Add(Id)
Id = ""
Next
'You can Check for duplicates by adding this piece of code or use the next one instead
Dim NoDupesIDsList As New List(Of String)
NoDupesIDsList = IDsList.Distinct.ToList
For i As Integer = 0 To 999 'This is a Zero Based Index so 999 is actually 1000
For _i As Integer = 0 To 7 'This also means 7 is 8
Id += Characters(Rand.Next(0, 36))
Next
If not IDsList.contains(Id) then
IDsList.Add(Id)
End if
Id = ""
Next
Use a Textbox with multiline and scroll bar for better experience
Feel free to ask me anything via comments
PS: I tested my method and it's working , enjoy it !
This function will return the ASCII characters between 48 an 122. That will include some characters that are not letters or numbers but this makes the ids even more unique and simplifies the code.
The For loop builds the ids with a length of 8. Then the id is checked for uniqueness with the .Contains method. Only if it is not in the list, it is added to the list and the counter is incremented.
Private Rnd As New Random
Private Function GetListOfIDs() As List(Of String)
Dim Counter As Integer
Dim lst As New List(Of String)
Dim id As String = ""
Do While Counter < 1000
id = ""
For i = 0 To 7
id &= Chr(Rnd.Next(48, 123))
Next
If Not lst.Contains(id) Then
lst.Add(id)
Counter += 1
End If
Loop
Return lst
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim lst = GetListOfIDs()
TextBox1.Text = String.Join(vbCrLf, lst)
End Sub
EDIT
As per suggestion by Caius Jard in comments I have added a solution using a HashSet. Same idea only a HashSet will not accept duplicate entries. The .Add method returns a boolean telling you if the Add was successful.
Private Function GetListOfIDs() As HashSet(Of String)
Dim hs As New HashSet(Of String)
Dim id As String = ""
Do While hs.Count < 1001
id = ""
For i = 0 To 7
id &= Chr(Rnd.Next(48, 123))
Next
If hs.Add(id) Then
Counter += 1
End If
Loop
Return hs
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim hs = BuildHashSet()
TextBox1.Text = String.Join(vbCrLf, hs)
End Sub
This method is probably more efficient because a HashSet is designed for hight performance. For 1000 items I did not notice any difference in the user interface. The text box updated immediately with both methods.
This will create the names:
Function RandomName(length As Integer) As String
Shared rnd As New Random()
Shared corpus() As Char = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".ToCharArray()
Return New String(Enumerable.Range(0, length).Select(Function(c) corpus(rnd.Next(corpus.Length))).ToArray())
End Function
Iterator Function GetUniqueNames(length As Integer, count As Integer) As IEnumerable(Of String)
Dim names As New HashSet(Of String)
For i As Integer = 0 To count
Dim name As String = RandomName(length)
While names.Contains(name)
'Potential (but unlikely) halting problem
name = RandomName(length)
End While
names.Add(name)
Yield name
Next
End Function
Dim uniqueNames = GetUniqueNames(8, 1000)
But do you really want to display 1000 of them in a single label?
lblRandomId.Text = string.Join(vbCrLf, uniqueNames)
Let's talk about your code.
Dim strChar As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
This assignment will work in your loop because a String is really an array of Char. This is why you can refer to an index in the string.
Dim rand As New Random()
The .net Random class provides a seed for Random based on system time. Only rarely would you want to provide a seed.
From the docs https://learn.microsoft.com/en-us/dotnet/api/system.random?view=netcore-3.1
CONSTRUCTORS
Random() Initializes a new instance of the Random class
using a default seed value.
Random(Int32) Initializes a new instance of the Random class, using
the specified seed value.
For count_ids As Integer = 0 To 999
A For loop is not appropriate for this problem. We only want to increment the counter if we get a unique ID. The above For loop will increment on every iteration.
Do While Counter < 1000
'Code here
Loop
Notice in my code the counter is only incremented if the ID is unique.
The following loop should work fine but above this code we need to reset strID to an empty string. Otherwise we will have a very long string.
For count_chars As Integer = 0 To 7
strID += strChar(rand.Next(0, 62))
Next count_chars
You should not update the user interface (the label) on each iteration of the loop. Repainting the screen is one of the slowest operations in code. This line will overwrite the string in the label on every iteration.
lblRandomId.Text = strID
Move the update of the UI to after both loops are complete
Your code never checks for duplicates.
Now let's fix it.
We use a List(Of T) to accumulate the IDs. The T stands for Type; in our case it is String. A List is like an array only you don't have to know ahead of time how many entries there will be. No ReDim Preserve required.
Moved Dim strID As String = "" to the beginning of the inner loop so we will get a new strID on each iteration of the outer loop.
Changed strID &= strChar(rand.Next(0, 62)). &= instead of +=. In VB.net we use the ampersand to concatenate strings although the plus sign will work. The .Next method of the Random class has an overload that takes 2 Integers. It is inclusive of the first and exclusive of the second which means (0, 62) will return numbers form 0 to 61. Your string with a length of 62 has indexes of 0 to 61.
Next we check for duplicates with the .Contains method of the List class. This method does just what you would expect. We pass the new ID to the method and it returns a Boolean telling if the string is already in the list.
If it is not in the list, we add it to the list and increment the counter. The counter is only incremented if we have a successful add.
Finally we update the user interface by using a method of the String class. the .Join method takes a separator and the list to join. The TextBox must be multiline and have scroll bars.
I changed the names of the controls so I could test it in my testing program.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim lst As New List(Of String)
Dim strChar As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Dim rand As New Random()
Dim counter As Integer
Do While counter < 1000
Dim strID As String = ""
For count_chars = 0 To 7
strID &= strChar(rand.Next(0, 62))
Next
If Not lst.Contains(strID) Then
lst.Add(strID)
counter += 1
End If
Loop
TextBox1.Text = String.Join(vbCrLf, lst)
End Sub
EDIT
The official documentation for this method can be found here.
https://learn.microsoft.com/en-us/dotnet/api/system.string.join?view=netcore-3.1
I know it will be difficult to read but just take a look. Eventually you will be able to understand it and will be using these docs a lot.
String.Join(separator, List(Of String))
The separator is what to put between the strings in the list. In our case that is vbCrLf which is a vb constant for new line. Cr = Carraiage Return and Lf = Line Feed. Other types of collections that contain strings can also use this method.
The method takes each string in the list and adds the separator. After it is done with the list it returns one long string which we display in the TextBox.
I've got a password generator in one of my scripts which generates 2 passwords and writes them to a database.
These passwords are later retrieved and set as the windows logon passwords for 2 users which are automatically created in a virtual machine.
I have a problem whereby my passwords are not always considered to be complex as far as windows is concerned.
I am using the following function to generate my passwords...
Public Function GeneratePassword(ByVal len As Integer) As String
Dim str As String = "1234567890qwertyuio1pa2sd3fg4hj5kl6zx7cv8bn9mQ0WE1RT2YU3IO4PA5SD6FG7HJ8KL9ZX0CVBNM"
Dim N As Integer = str.Length
Dim rnd As New Random((Now.Hour * 3600 + Now.Minute * 60 +
Now.Second) * 1000 + Now.Millisecond)
Dim sb As New StringBuilder
For l As Integer = 1 To len
sb.Append(str.Substring(rnd.Next(0, N), 1))
Next
Return sb.ToString
End Function
Which is then called like this...
Dim vm_password1 As String = GeneratePassword(10)
How would i best go about modifying this code to ensure that each password generated contains 1 uppercase character, 1 lowercase character and one number?
Any help appreciated! :)
Of course you can extend this further, but here's the jist
Public Function fnGenPw() As String
Dim RandomClass As New Random()
Const legalAlpha As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
Const legalNums As String = "1234567890"
Dim strbNewpw As New StringBuilder
For i As Integer = 0 To 2 'first 3 characters are alpha
Dim RandomNumber As Integer = RandomClass.Next(legalAlpha.Length - 1)
strbNewpw.Append(legalAlpha.Chars(RandomNumber))
Next
For i As Integer = 3 To 5 'characters 4,5,6 are numeric
Dim RandomNumber As Integer = RandomClass.Next(legalNums.Length - 1)
strbNewpw.Append(legalNums.Chars(RandomNumber))
Next
For i As Integer = 6 To 9 'characters 7,8,9,10 are alpha
Dim RandomNumber As Integer = RandomClass.Next(legalAlpha.Length - 1)
strbNewpw.Append(legalAlpha.Chars(RandomNumber))
Next
Return strbNewpw.ToString
End Function
I want to generate a random number of 6 intergers in vb.net which should be number and also some times alphanumerice.Like ist 4 or 5 numbers should be numbers and next should be alphnumeric.I created both numbers separatedly.like this
Public Function rand() As String
'Number
Dim rng As Random = New Random
Dim number As Integer = rng.Next(1, 1000000)
Dim digits As String = number.ToString("000000")
'Alphnumeric
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
Dim r As New Random
Dim sb As New StringBuilder
For i As Integer = 1 To 5
Dim idx As Integer = r.Next(0, 35)
sb.Append(s.Substring(idx, 1))
Next
End Function
Now Any One Give Me Idea that in this function can i return number and some times string or may b a single instances which create both numbers and strings.
The first problem to solve is the random number generator. You should use only one instance and not multiple instances that gives back the same sequence if called in short time distance. Then it is
difficult to say what 'something' means in your requirements, but supposing you are fine with rougly 70% numbers and 30% a mix of numbers and strings then you call the random generator to decide for a sequence of only numbers or a mixed one. Based on the output of the random selection of the sequence build from the appropriate string
' A global unique random generator'
Dim rng As Random = New Random
Sub Main
Console.WriteLine(rand())
Console.WriteLine(rand())
Console.WriteLine(rand())
Console.WriteLine(rand())
End Sub
Public Function rand() As String
Dim sb As New StringBuilder
' Selection of pure numbers sequence or mixed one
Dim pureNumbers = rng.Next(1,11)
if pureNumbers < 7 then
' Generate a sequence of only digits
Dim number As Integer = rng.Next(1, 1000000)
Dim digits As String = number.ToString("000000")
For i As Integer = 1 To 6
Dim idx As Integer = rng.Next(0, digits.Length)
sb.Append(digits.Substring(idx, 1))
Next
else
' Generate a sequence of digits and letters
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
For i As Integer = 1 To 6
Dim idx As Integer = rng.Next(0, 36)
sb.Append(s.Substring(idx, 1))
Next
End if
return sb.ToString()
End Function
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
Good afternoon,
How can i split a value and insert it into a array in VB?
An example:
The initial value is 987654321.
Using a for loop i need to insert the value as something like this:
Position(1) = 9 'The first number from the splited integer
Position(2) = 8 'The second number from the splited integer
and so on...
Thank you.
This code is untested:
Dim x As Integer = 987654321
Dim s As String = x.ToString
Dim a(s.Length) As String
For i As Integer = 0 To s.Length - 1
a(i) = s.Substring(i, 1)
Next i
You could try:
Dim number As Integer = 987654321
Dim strText As String = number.ToString()
Dim charArr() As Char = strText.ToCharArray()
Once the numbers are separated, you can then pull them out from this array and convert them back to numbers if you need to.
Dim number As Integer = 987654321
Dim digits() As Integer = number.ToString().Cast(Of Integer)().ToArray()
Will show any number separated in 3 different message box.
You can make a function with the example to better suit your purpose.
Sub GetNumber()
Dim x As Integer, s As String
x = 987
s = LTrim(Str(x))
For i = 1 To Len(s)
MsgBox Mid(s, i, 1)
Next i
End Sub
I know this is an old question, but here is the most elegant solution I could get to work:
Dim key As Integer = 987654321
Dim digits() As Integer = System.Array.ConvertAll(Of Char, Integer)(key.ToString.ToCharArray, Function(c As Char) Integer.Parse(c.ToString))