Modify string

[Mekinnik]

How would I go about modifing a string with code? Lets say I have a string '12345' and I want to change the 3 to a six. How could I accomplish this task. I know how to grab the 3 itself and change it as a variable and I know how to get the postion of the 3, but how would I change the string itself within the code? I am looking to pass the string as a value to the function I am working on. Any thoughts on how to do this?

Thanks for any help or ideas given

[DataMiser]

You could use replace()

Syntax

Replace(expression, find, replacewith[, start[, count[, compare]]])


You could also use the Mid() statement

Mid Statement Example
This example uses the Mid statement to replace a specified number of characters in a string variable with characters from another string.

Dim MyString
MyString = "The dog jumps"   ' Initialize string.
Mid(MyString, 5, 3) = "fox"   ' MyString = "The fox jumps".
Mid(MyString, 5) = "cow"   ' MyString = "The cow jumps".
Mid(MyString, 5) = "cow jumped over"   ' MyString = "The cow jumpe".
Mid(MyString, 5, 3) = "duck"   ' MyString = "The duc jumpe".

[Mekinnik]

DataMiser,
Thanks for the reply. The issue I have now is how to return the modified string back to the function that called it. Here is what I have currently, the function that calls, and the function that returns. When the function NumeralTest(RetVal) returns true it then calls the function ReplNum(RetVal). I am trying to modify the string 'RetVal', then return it to the calling function where it will then move through the other function to be evaluated. Here is what I have.

Public Function GetPassword() As String

Dim RetVal As String
Dim rgch As String
Dim i As Integer
Dim totalLength As Integer

  Randomize

    '***********************************************
    'Fills the string 'rgch' with the approved characters to
    'choose for the string 'RetVal'.
    '***********************************************
  rgch = "abcdefghijklmnopqrstuvwxyz"
  
  rgch = rgch + UCase(rgch) + "123456789" + "!#$*+,;:<=>?@^_|~"
  
    '***********************************************
    'Generates a random number from 15 to 32, to be
    'used for the password string length.
    '***********************************************
  totalLength = Int((32 - 15 + 1) * Rnd() + 15)
   
   For i = 1 To totalLength 'counter for the total string length
    
    '***********************************************
    'Fills the string 'RetVal' with the generated
    'alphanumeric string.
    '***********************************************
          
  RetVal = RetVal + Mid$(rgch, Int(Rnd() * Len(rgch) + 1), 1)

Next
'***************************************************
'Create two functions to add missing values if returned FALSE.
'***************************************************
    If Not NumeralTest(RetVal) Then
     Call ReplNum(RetVal)
     ElseIf Not SpecialChrTest(RetVal) Then
     'Do Something
      ElseIf Not AlphaChrTest(RetVal) Then
        'Do Something
       'ElseIf Not AcrNimTst(RetVal) Then
         'Do Something
     End If
      
GetPassword = RetVal
End Function

And the called funtion

Private Function ReplNum(ByVal RetVal As String) As String
Dim i, x, z, w, a, count As Integer
Dim test, bustest As String

'**********************************************
'Numeral error section. Determines how many numerals _
are needed to be either inserted or replaced within _
the string 'RetVal'.
'**********************************************
z = 0
test = "123456789"
'w = InStr(RetVal, test)
For i = 1 To Len(RetVal)
  bustest = Mid$(RetVal, i, 1)
   If InStr(test, bustest) Then
     count = count + 1
      End If
        Next
        
 If count = 0 Then
  Do While z < 2
   z = z + 1
    Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the character/number value of 'x'

Loop
  ElseIf count = 1 Then
   Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the character/number value of 'x'
End If
Return RetVal
End Function

[DataMiser]

When you are calling a function you need to use a variable to hold the result. Instead of

Call ReplNum(RetVal)

You would want to use something more like

RetVal = ReplNum(RetVal)

[Mekinnik]

DataMiser,
I tried what you suggested, but it is not returning the modified string. Any ideas as to what I am doing wrong? Here is what I have now, the sub, the calling function, and the called function:

Option Explicit
Public Sub CmdBtn1_Click()
Dim RepVal As String
    '***********************************************
    'Figure out how to make the textbox hidden
    'until 'password' has passed all the business rules
    'at which point, the textbox window will become
    'visable and a message will be thrown letting the
    'user know to use the shown password. Then the user
    'name and password will be copied to the data base
    'and the copy button will become active to allow the
    'user to copy and paste the password
    '************************************************
 
 
RepVal = GetPassword
         
    TxtBx.Text = RepVal
End Sub

Public Function GetPassword() As String

Dim RetVal, RepVal As String
Dim rgch As String
Dim i As Integer
Dim totalLength As Integer

  Randomize

    '***********************************************
    'Fills the string 'rgch' with the approved characters to
    'choose for the string 'RetVal'.
    '***********************************************
  rgch = "abcdefghijklmnopqrstuvwxyz"
  
  rgch = rgch + UCase(rgch) + "123456789" + "!#$*+,;:<=>?@^_|~"
  
    '***********************************************
    'Generates a random number from 15 to 32, to be
    'used for the password string length.
    '***********************************************
  totalLength = Int((32 - 15 + 1) * Rnd() + 15)
   
   For i = 1 To totalLength 'counter for the total string length
    
    '***********************************************
    'Fills the string 'RetVal' with the generated
    'alphanumeric string.
    '***********************************************
          
  RetVal = RetVal + Mid$(rgch, Int(Rnd() * Len(rgch) + 1), 1)

Next
'***************************************************
'Create two functions to add missing values if returned FALSE.
'***************************************************
    If Not NumeralTest(RetVal) Then
     RepVal = ReplNum(RetVal)
     'ElseIf Not SpecialChrTest(RetVal) Then
     'Do Something
      'ElseIf Not AlphaChrTest(RetVal) Then
        'Do Something
       'ElseIf Not AcrNimTst(RetVal) Then
         'Do Something
     End If
 

End Function

Private Function ReplNum(ByVal RetVal As String) As String
Dim i, x, z, w, a, count As Integer
Dim test, bustest As String

'**********************************************
'Numeral error section. Determines how many numerals _
are needed to be either inserted or replaced within _
the string 'RetVal'.
'**********************************************
z = 0
test = "123456789"
'w = InStr(RetVal, test)
For i = 1 To Len(RetVal)
  bustest = Mid$(RetVal, i, 1)
   If InStr(test, bustest) Then
     count = count + 1
      End If
        Next
        
 If count = 0 Then
  Do While z < 2
   z = z + 1
    Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the character/number value of 'x'

Loop
  ElseIf count = 1 Then
   Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the character/number value of 'x'
End If

End Function

[DataMiser]

You need to make sure that you code the function to return the password. That line is missing from your getpassword function

as the last line of code prior to end function try

GetPassword=RetVal

Looks like it is also missing from your other function now as well.


Edit to add:
Looking at the first post I see the line Return RetVal which apparently I mistook to be valid as this is the proper way in VB.Net but that line is now missing and the proper line was not added.

[DataMiser]

Keep in mind that subs do not return a value. When you use a sub you can either just reference them by name or you can use the Call keyword.

A function is designed to return a value of a specified type. When you create a function you must specify what type of value it will return.

At some point inside the function this value must be assigned to the function for return.
As a general rule all functions should always return a value even if that value is false, null or empty string.

Public MyFunction(PassMeData AS String) AS String

Dim ResultString as String

' do some stuff here that will populate our resultstring

MyFunction=ResultString
End Function

Anytime you call a function you should have a variable of the proper type to hold the returned data that results from the function call and then do whatever you need to do with that data.

Dim MyResultString as string
Dim MYParamString as string

MyResultString=MyFunction(MyParamString)

MyResultString will contain the string that is returned from the function.

[Mekinnik]

DataMiser,
Thank you for the help. It worked out perfectly. I was just missing the function returns like you suggested. Thanks a million.

[Mekinnik]

Another question within my modify string function. If 'a' creates the position within the string 'RetVal' to be modified, how can I test to see if the position 'a' already has a numeral? The following lines creates a random number 'x' to replace position 'a' within the string 'RetVal'. Any thoughts??

'If 'a' equals the position of an existing numeral _
then have it generate another position
  
ElseIf count = 1 Then
   Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the value of 'x'
End If

[DataMiser]

Use can use the mid function and isnumeric() function for this or you could use the instr() function and mid() function.

In the case of the latter you could do something like

if instr("0123456789",mid(MyString,a,1))>0 then
   'there is a numeral in that position
else
   'the character there is not a numeral
end if

[Mekinnik]

Datamiser,
Thank for your suggestion, it works great. In continuing with the modify string issue, the second function has to insert a special character. Here is my code for your review. Right now it is basiclly a copy of the numeral replace function. I am open to any suggestions you might have.

Thanks

Private Function ReplSpc(ByVal RetVal As String) As String
Dim i, x, z, a, count As Integer
Dim bustest As String

'**********************************************
'Special Character error section. Determines how many _
special characters are needed to be either inserted _
or replaced within the string 'RetVal'.
'**********************************************
'Choose a random number from a pool of numbers? _
The pool consists of 35, 36, 42-46, 58-64, 94, 95, 124, 126
Const test As String = "!#$*+,;:<=>?@^_|~"

For i = 1 To Len(RetVal)
  bustest = Mid$(RetVal, i, 1)
   If InStr(test, bustest) Then
     count = count + 1
      End If
        Next
        
 If count = 0 Then
   z = 0
  Do While z < 2
   z = z + 1
    Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the character 'x'

Loop
'If 'a' equals the position of an existing numeral _
then have it generate another position
  ElseIf count = 1 Then
   Randomize
     a = Int((Len(RetVal) - 1 + 1) * Rnd() + 1)
      x = Int((9 - 1 + 1) * Rnd() + 1) 'Produces a _
random number between 1 and 9

       Mid(RetVal, a, 1) = x 'Replaces the character at _
position 'a' with the character 'x'
End If
ReplSpc = RetVal
End Function

[Mekinnik]

DataMiser,
Never mind I figured it out myself.

Thanks, anyway

Const test2 As String = "!#$*+,;:<=>?@^_|~"

x = Mid$(test2, Int(Rnd() * Len(test2) + 1), 1)