I`m having the following code from which I extract randomPW for my db.
I need this string of random characters in order to use it a primary key in my Db. The problem is that I`m getting quite a lot of duplicates when I execute this code more than once or if I get a Loop in order to extract (for example) 100 keys at once.
If I try to reload the page in order to insert one by one key the same problem occurs... every 50-80 reloads there is a duplicate. What's wrong with my code?
<%
Function RandomPW(myLength)
Const minLength = 6
Const maxLength = 20
Dim X, Y, strPW
If myLength = 0 Then
Randomize
myLength = Int((maxLength * Rnd) + minLength)
End If
For X = 1 To myLength
Y = Int((3 * Rnd) + 1) '(1) Numeric, (2) Uppercase, (3) Lowercase
Select Case Y
Case 1
'Numeric character
Randomize
strPW = strPW & CHR(Int((9 * Rnd) + 48))
Case 2
'Uppercase character
Randomize
strPW = strPW & CHR(Int((25 * Rnd) + 65))
Case 3
'Lowercase character
Randomize
strPW = strPW & CHR(Int((25 * Rnd) + 97))
End Select
Next
RandomPW = strPW
End Function
%>
I expect my code to extract a string that will not duplicate every now and then.
I need this string of random characters in order to use it a primary key in my Db.
In this case I would recommend to use Scriptlet.TypeLib :
Function RandomPW(myLength)
Set TypeLib = CreateObject("Scriptlet.TypeLib")
If myLength < Len(TypeLib.Guid)
RandomPW = Left(TypeLib.Guid, myLength)
Else
RandomPW = TypeLib.Guid
End If
End Function
Randomize is not supposed to be used more than once, unless you want to make sure you are creating fake, repeatable randomness. Per docs, helpfully linked by Lankymart (emphasis mine):
Randomize uses number to initialize the Rnd function's random-number generator, giving it a new seed value. If you omit number, the value returned by the system timer is used as the new seed value.
The system timer referred to above is in seconds; which means, successive calls to Randomize in short succession will make sure the following Rnd is yielding the same value.
It would likely help you immensely to remove all calls to Randomize.
I'm new to vbscript.
I've got this so far
Function random_number_generator (lowerLim, upperLim)
Randomize
randNumber = Int(((upperLim-lowerLim+1)* Rnd())+ lowerLim)
random_number_generator = randNumber
End Function
But how do I make it to have a sequence for generating let's say 9 digit social security number?
for example if the first social security is 200030886 next would be 200030887 and so on.
I'm not sure why you have a random element to your question. I seems like you just want a counter?
Dim start, ends
start = 200030886
ends = 200040000
for k = start to ends
MsgBox k
next
If you need a random number formatted like the numbers above, you can try this.
MsgBox random_number_generator(1, 10000)
Function random_number_generator (lowerLim, upperLim)
Randomize
randNumber = Int(((upperLim-lowerLim+1)* Rnd())+ lowerLim)
random_number_generator = "2" & RIGHT("000000000" & randNumber, 8)
End Function
Hope that helps
Dim RandNumber
RandNumber = RandomNumber(1,10000)
Print RandNumber
Here's part of my code.
<%
Dim lineData,fso,filea,fileb,filec
s=request.querystring("query")
set fso = Server.CreateObject("Scripting.FileSystemObject")
a(0,0)=0
a(1,0)=" - Entries in File A"
set filea = fso.OpenTextFile(Server.MapPath("FileA.txt"), 1, true)
do until lone.AtEndOfStream
lineData = lcase(filea.ReadLine())
if instr(lineData,s)>0 then
a(0,0)=a(0,0)+1
end if
Loop
a(0,1)=0
a(1,1)=" - Entries in File B"
set fileb = fso.OpenTextFile(Server.MapPath("FileB.txt"), 1, true)
do until mile.AtEndOfStream
lineData = lcase(fileb.ReadLine())
if instr(lineData,s)>0 then
a(0,1)=a(0,1)+1
end if
Loop
a(0,2)=0
a(1,2)=" - Entries in File C"
set filec = fso.OpenTextFile(Server.MapPath("FileC.txt"), 1, true)
do until payne.AtEndOfStream
lineData = lcase(filec.ReadLine())
if instr(lineData,s)>0 then
a(0,2)=a(0,2)+1
end if
Loop
%>
The code essentially looks for the number of entries in a text file. What I need is it to be sorted such that the file with the most number of entries comes first.
Suppose there are 10 entries in FileA, 12 in FileB and 7 in FileC. I'd like the output to be displayed like this:
12 - Entries in File B
10 - Entries in File A
7 - Entries in File C
I'm guessing it won't be too complicated since response.write(a(0,i)&a(1,i)) will work. I just need help with the loop or any sorting method if there is one.
Any help I can get in here will be much appreciated.
This will be a "neo-answer" that should help you get to where you want to go, both in the short- and long-term.
1) First, a suggestion for further reading to help you address this sort of problem in a more general way -- and to help you develop your "chops" as you go. You can Google the term "bubble sort" and get a whole host of interesting and mostly helpful input, but here's a link you probably will find most directly helpful, from a brief series of articles on sorting from the 4 Guys from Rolla site, which back in the day was THE place for quality writing on ASP:
https://web.archive.org/web/20211020153403/https://www.4guysfromrolla.com/webtech/011601-1.shtml
You will see that there is a link to an introductory article at the top of this one that covers one-dimensional array sorting, and I recommend it as well. For one, it introduces another sort method, QuickSort, and having multiple tools in your toolbox is almost never a bad idea. (As you will discover, bubble sorting is often the easiest to envision and implement, but because its performance is essentially linear based on the number of items being sorted, can become a performance problem on larger datasets.) Go ahead, check it out; I'll wait 'til you get back...
2) OK, to give you a more concrete approach to address your specific situation here, if the number of files you're reviewing isn't going to be too large, you can do a sort of "final pass" sort to present your results in the desired order.
First, you'll want to introduce a simple global counting variable up toward the top of your code:
dim intMaxEntries
intMaxEntries = 0
Then, at the end of each of your file-parsing runs, you'll want to check the number of entries against intMaxEntries and update intMaxEntries if the number of entries just read in is greater.
if a(0, 1) > intMaxEntries then
intMaxEntries = a(0, 1)
end if
You'll do right after each file reading loop, so the comparison in the above snippet would be done for a(0, 1), a(1, 1), and a(2, 1). More on that repetitive logic at the end.
After you've done all the file reads, intMaxEntries will have the maximum number of entries you've found in one of the files. Then, you can just step down from that value and print out entry counts in the correct order when they match your countdown:
dim i, j
for i = intMaxEntries to 0 step -1
for j = 0 to ubound(a) 'By default gives the upper bound of the 1st dimen.
if a(j, 1) = i then
Response.Write i & a(j, 2) & "<BR>"
end if
next j
next i
This is more than a bit of a hack, and I would encourage you to opt instead for doing a proper sort of your array so that you have something more generalizably useful, but it will work to get you where you want to go, especially if the number of files -- or the maximum number of entries -- isn't too large. You could also clean up my example by introducing the possibility of breaking out of the loops when all the files are accounted for, but I'll let you figure out if that's necessary.
3) You may have just simplified the codebase to get the concept across more cleanly (for which I applaud you if true), but just in case, I would encourage you to look at ways to modularize your work by building your file reading functionality as a function that is simply called with the file and string comparison information needed. (Also, probably an artifact of your snipping, but the "lone", "mile" and "Payne" references in there don't make sense; assuming those are the FSOs you are instantiating and have just forgotten to change them to fileA, fileB and fileC.)
Hope that helps a bit,
Bret
#bret
Someone else came through.
Here's a code that worked perfectly.
Would this be an example of "bubble sort"?
for k=23 to 0 Step-1
for j=0 to k
if (a(0,j)<a(0,j+1)) then
t1=a(0,j+1)
t2=a(1,j+1)
a(0,j+1)=a(0,j)
a(1,j+1)=a(1,j)
a(0,j)=t1
a(1,j)=t2
end If
next
next
for i=0 to 24
if a(0,i)>0 then
response.write (a(0,i)&a(1,i)&"<br>")
end if
next
set objFSO = Server.CreateObject("Scripting.FileSystemObject")
set objFolder = objFSO.GetFolder(server.mappath("Files"))
set objfiles = objFolder.Files
Function filesearch(name)
set searchname = objFSO.OpenTextFile(server.mappath(filename),1, true)
do until searchname.AtEndOfStream
lineData = lcase(searchname.ReadLine())
if instr(lineData,s)>0 then
instances = instances + 1
end if
Loop
End Function
For Each objFile in objFolder.Files
filesearch(objFile)
Response.Write filename & "<br>" & instances & "<br>" & "<br>"
Next
Set objFolder = Nothing
Set objFSO = Nothing
There are a few rough edges but what really bothers me now is the sorting. Where do I keep the bubble sort code?
EDIT:
I've got it work perfect with the following code.
For Each objFile in objFolder.Files
filesearch(objFile)
i = i + 1
a(0,i) = instances
a(1,i) = filename
Next
I was also wondering if there's anyway I could also write the total number of instances. I was able to do it before with:
for i=0 to 43
entries=entries+a(0,i)
next
I cant seem to make it work now.
EDIT:
Works now with:
for i = 0 to n
entries = entries + a(0,i)
next
So I have this function which generates a random string of digits 8 characters long. It works if its called once per page, ie if I refresh it will show a new number.
But I want to generate many of these inside a loop and its returning the same number. How can I solve this?
Function generateCode()
pChar = "0123456789"
pCount = Len(pChar)
Dim psw
psw = ""
Randomize
For i = 1 To 8 ' password length
psw = psw & Mid( pChar, 1 + Int(Rnd * pCount), 1 )
Next
generateCode= psw
End Function
Now I thought Randomize may be based off the current time, so I took the Randomize line out and called Randomize before the loop that calls generateCode() i- still didn't work!
Randomize without any arguments seeds the pseudo-random number generator using the system time. If you call it multiple times very quickly the system time won't have changed so you will reinitialize the PRNG with the same seed each time, giving the same random numbers.
You should only call Randomize only once on your page, not multiple times.
I have the following structures defined (names are anonymised, but data types are correct):
Public Type ExampleDataItem
Limit As Integer ' could be any value 0-999
Status As Integer ' could be any value 0-2
ValidUntil As Date ' always a valid date
End Type
Public Type ExampleData
Name As String ' could be 5-20 chars long
ValidOn As Date ' could be valid date or 1899-12-30 representing "null"
Salt As Integer ' random value 42-32767
Items(0 To 13) As ExampleDataItem
End Type
I would like to generate a 32-bit hash code for an ExampleData instance. Minimising hash collisions is important, performance and data order is not important.
So far I have got (in pseudocode):
Serialise all members into one byte array.
Loop through the byte array, reading 4 bytes at a time into a Long value.
XOR all the Long values together.
I can't really post my code because it's heavily dependent on utility classes to do the serialisation, but if anyone wants to see it regardless then I will post it.
Will this be OK, or can anyone suggest a better way of doing it?
EDIT:
This code is being used to implement part of a software licensing system. The purpose of the hash is to confirm whether the data entered by the end user equals the data entered by the tech support person. The hash must therefore:
Be very short. That's why I thought 32 bits would be most suitable, because it can be rendered as a 10-digit decimal number on screen. This is easy, quick and unambiguous to read over the telephone and type in.
Be derived from all the fields in the data structure, with no extra artificial keys or any other trickery.
The hash is not required for lookup, uniqueness testing, or to store ExampleData instances in any kind of collection, but only for the one purpose described above.
Can you use the CRC32? Steve McMahon has an implementation. Combine that with a bit of base32 encoding and you've got something short enough to read over the phone.
Considering that performance is not an objective, if file size is not important and you want a unique value for each item. Just add an ID field. It data type is a string. Then use this function to generate a GUID. This will be a unique ID. Use it as a key for a dictonary or collection.
Public Type GUID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(7) As Byte
End Type
Public Type GUID2 '15 BYTES TOTAL
Data1(14) As Byte
End Type
Public Declare Function CoCreateGuid Lib "OLE32.DLL" (pGuid As GUID) As Long
Public Function GetGUID() As String
Dim VBRIG_PROC_ID_STRING As String
VBRIG_PROC_ID_STRING = "GetGUID()"
Dim lResult As Long
Dim lguid As GUID
Dim MyguidString As String
Dim MyGuidString1 As String
Dim MyGuidString2 As String
Dim MyGuidString3 As String
Dim DataLen As Integer
Dim StringLen As Integer
Dim i As Integer
On Error GoTo error_olemsg
lResult = CoCreateGuid(lguid)
If lResult = 0 Then
MyGuidString1 = Hex$(lguid.Data1)
StringLen = Len(MyGuidString1)
DataLen = Len(lguid.Data1)
MyGuidString1 = LeadingZeros(2 * DataLen, StringLen) & MyGuidString1
'First 4 bytes (8 hex digits)
MyGuidString2 = Hex$(lguid.Data2)
StringLen = Len(MyGuidString2)
DataLen = Len(lguid.Data2)
MyGuidString2 = LeadingZeros(2 * DataLen, StringLen) & Trim$(MyGuidString2)
'Next 2 bytes (4 hex digits)
MyGuidString3 = Hex$(lguid.Data3)
StringLen = Len(MyGuidString3)
DataLen = Len(lguid.Data3)
MyGuidString3 = LeadingZeros(2 * DataLen, StringLen) & Trim$(MyGuidString3)
'Next 2 bytes (4 hex digits)
GetGUID = MyGuidString1 & MyGuidString2 & MyGuidString3
For i = 0 To 7
MyguidString = MyguidString & Format$(Hex$(lguid.Data4(i)), "00")
Next i
'MyGuidString contains last 8 bytes of Guid (16 hex digits)
GetGUID = GetGUID & MyguidString
Else
GetGUID = "00000000" ' return zeros if function unsuccessful
End If
Exit Function
error_olemsg:
GetGUID = "00000000"
Exit Function
End Function
Public Function LeadingZeros(ExpectedLen As Integer, ActualLen As Integer) As String
LeadingZeros = String$(ExpectedLen - ActualLen, "0")
End Function
EDIT: the question has now been edited to clarify that the goal is detecting typing errors, not minimizing collisions between totally different values. In that case Dan F's answer is the best one IMHO, not my offering below (wonderful though it is).
You could use the Microsoft CryptoAPI rather than rolling your own hash algorithm.
For instance this Microsoft article on using CryptoAPI from VB6 should get you started.
Or this from Edanmo on mvps.org for hashing a string in VB6.
EDIT: Following comment. If you insist on a 32-bit value, it will be hard to minimize hash collisions. My algorithm book suggests using Horner's method as a decent general purpose hashing algorithm. I don't have time right now to find out more information and implement in VB6. CopyMemory would probably be useful :)
You may be overthinking it, or I'm not understanding the issue. You could essentially just
hash(CStr(Salt) + Name + CStr(ValidOn) + Anyotherstrings
There is no particular need to go through the process of serializing into byte array and XORing values. Infact XORing values together in that way is more likely to create hash collisions where you aren't intending them.
Edit: I think I understand now. You're creating your own hash value by XORing the data together? It's unfortunately quite likely to give collisions. I know VB6 doesn't include any hashing algorithms, so you may be best importing and using something like Phil Fresle's SHA256 implementation.