validating textbox

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  • ameen.abdullah@gmail.com
    #1

    validating textbox

    Hi Guys,

    I have a textbox in windows form that should only accept alphabets,
    numbers, spaces and underscore. If the textbox contains anyother
    character it should display a msg at the time of validation.. Is there
    any funciton in vb.net for this? or any other way??


    Waiting for ur replies...

    Thanks in adv.

    Tags: None
    • Siva M
      #2
      Re: validating textbox

      There are at least couple of ways to do this: 1. Filtering the charaters in
      the Keypress event of the textbox itself 2. Using regular expressions to
      find invalid character in the textbox. See which one works ut for you...

      <ameen.abdullah @gmail.comwrote in message
      news:1156777910 .929069.214270@ i42g2000cwa.goo glegroups.com.. .
      Hi Guys,

      I have a textbox in windows form that should only accept alphabets,
      numbers, spaces and underscore. If the textbox contains anyother
      character it should display a msg at the time of validation.. Is there
      any funciton in vb.net for this? or any other way??


      Waiting for ur replies...

      Thanks in adv.

        Comment

        • Dennis
          #3
          Re: validating textbox

          Using the KeyPress event does not preclude the user from cutting from some
          other source and pasting invalid chars into the text box. Use the textbox's
          "Validating " event to check the text for non-alpha characters.
          --
          Dennis in Houston


          "Siva M" wrote:
          There are at least couple of ways to do this: 1. Filtering the charaters in
          the Keypress event of the textbox itself 2. Using regular expressions to
          find invalid character in the textbox. See which one works ut for you...
          >
          <ameen.abdullah @gmail.comwrote in message
          news:1156777910 .929069.214270@ i42g2000cwa.goo glegroups.com.. .
          Hi Guys,
          >
          I have a textbox in windows form that should only accept alphabets,
          numbers, spaces and underscore. If the textbox contains anyother
          character it should display a msg at the time of validation.. Is there
          any funciton in vb.net for this? or any other way??
          >
          >
          Waiting for ur replies...
          >
          Thanks in adv.
          >
          >

            Comment

            • Claes Bergefall
              #4
              Re: validating textbox

              If you want to prevent illegal characters from being pasted you can use this
              code:

              Protected Overrides Function ProcessCmdKey(B yRef msg As
              System.Windows. Forms.Message, ByVal keyData As System.Windows. Forms.Keys) As
              Boolean
              'Need to prevent pasting of invalid characters
              If keyData = (Keys.Shift Or Keys.Insert) OrElse keyData =
              (Keys.Control Or Keys.V) Then
              Dim data As IDataObject = Clipboard.GetDa taObject
              If data Is Nothing Then
              Return MyBase.ProcessC mdKey(msg, keyData)
              Else
              Dim text As String =
              CStr(data.GetDa ta(DataFormats. StringFormat, True))
              If text = String.Empty Then
              Return MyBase.ProcessC mdKey(msg, keyData)
              Else
              For Each ch As Char In text.ToCharArra y
              If Not IsValid(ch) Then
              Return True
              End If
              Next
              Return MyBase.ProcessC mdKey(msg, keyData)
              End If
              End If
              Else
              Return MyBase.ProcessC mdKey(msg, keyData)
              End If
              End Function

              Private Function IsValid(ByVal ch As Char) As Boolean
              'TODO: Check if the character is valid
              End Function

              The above will prevent pasting if the text contains any illegal characters.

              /claes

              "Dennis" <Dennis@discuss ions.microsoft. comwrote in message
              news:DC678667-0480-457C-BF94-F403CC18DC80@mi crosoft.com...
              Using the KeyPress event does not preclude the user from cutting from some
              other source and pasting invalid chars into the text box. Use the
              textbox's
              "Validating " event to check the text for non-alpha characters.
              --
              Dennis in Houston
              >
              >
              "Siva M" wrote:
              >
              >There are at least couple of ways to do this: 1. Filtering the charaters
              >in
              >the Keypress event of the textbox itself 2. Using regular expressions to
              >find invalid character in the textbox. See which one works ut for you...
              >>
              ><ameen.abdulla h@gmail.comwrot e in message
              >news:115677791 0.929069.214270 @i42g2000cwa.go oglegroups.com. ..
              >Hi Guys,
              >>
              >I have a textbox in windows form that should only accept alphabets,
              >numbers, spaces and underscore. If the textbox contains anyother
              >character it should display a msg at the time of validation.. Is there
              >any funciton in vb.net for this? or any other way??
              >>
              >>
              >Waiting for ur replies...
              >>
              >Thanks in adv.
              >>
              >>

                Comment

                • Dennis
                  #5
                  Re: validating textbox

                  I believe you have to subclass the textbox to override the ProcessCmdKey
                  whereas with the validating event you don't have to do any subclassing. it's
                  easier to work with at design time.
                  --
                  Dennis in Houston


                  "Claes Bergefall" wrote:
                  If you want to prevent illegal characters from being pasted you can use this
                  code:
                  >
                  Protected Overrides Function ProcessCmdKey(B yRef msg As
                  System.Windows. Forms.Message, ByVal keyData As System.Windows. Forms.Keys) As
                  Boolean
                  'Need to prevent pasting of invalid characters
                  If keyData = (Keys.Shift Or Keys.Insert) OrElse keyData =
                  (Keys.Control Or Keys.V) Then
                  Dim data As IDataObject = Clipboard.GetDa taObject
                  If data Is Nothing Then
                  Return MyBase.ProcessC mdKey(msg, keyData)
                  Else
                  Dim text As String =
                  CStr(data.GetDa ta(DataFormats. StringFormat, True))
                  If text = String.Empty Then
                  Return MyBase.ProcessC mdKey(msg, keyData)
                  Else
                  For Each ch As Char In text.ToCharArra y
                  If Not IsValid(ch) Then
                  Return True
                  End If
                  Next
                  Return MyBase.ProcessC mdKey(msg, keyData)
                  End If
                  End If
                  Else
                  Return MyBase.ProcessC mdKey(msg, keyData)
                  End If
                  End Function
                  >
                  Private Function IsValid(ByVal ch As Char) As Boolean
                  'TODO: Check if the character is valid
                  End Function
                  >
                  The above will prevent pasting if the text contains any illegal characters.
                  >
                  /claes
                  >
                  "Dennis" <Dennis@discuss ions.microsoft. comwrote in message
                  news:DC678667-0480-457C-BF94-F403CC18DC80@mi crosoft.com...
                  Using the KeyPress event does not preclude the user from cutting from some
                  other source and pasting invalid chars into the text box. Use the
                  textbox's
                  "Validating " event to check the text for non-alpha characters.
                  --
                  Dennis in Houston


                  "Siva M" wrote:
                  There are at least couple of ways to do this: 1. Filtering the charaters
                  in
                  the Keypress event of the textbox itself 2. Using regular expressions to
                  find invalid character in the textbox. See which one works ut for you...
                  >
                  <ameen.abdullah @gmail.comwrote in message
                  news:1156777910 .929069.214270@ i42g2000cwa.goo glegroups.com.. .
                  Hi Guys,
                  >
                  I have a textbox in windows form that should only accept alphabets,
                  numbers, spaces and underscore. If the textbox contains anyother
                  character it should display a msg at the time of validation.. Is there
                  any funciton in vb.net for this? or any other way??
                  >
                  >
                  Waiting for ur replies...
                  >
                  Thanks in adv.
                  >
                  >
                  >
                  >
                  >

                    Comment

                    • Claes Bergefall
                      #6
                      Re: validating textbox

                      You're correct. The code below requires an override. If it is enough to
                      validate when they leave the field then using the Validating event is
                      easier. I just wanted to point out another option.

                      /claes

                      "Dennis" <Dennis@discuss ions.microsoft. comwrote in message
                      news:72A55D9A-CA67-45A7-92B9-2BC60FF95833@mi crosoft.com...
                      >I believe you have to subclass the textbox to override the ProcessCmdKey
                      whereas with the validating event you don't have to do any subclassing.
                      it's
                      easier to work with at design time.
                      --
                      Dennis in Houston
                      >
                      >
                      "Claes Bergefall" wrote:
                      >
                      >If you want to prevent illegal characters from being pasted you can use
                      >this
                      >code:
                      >>
                      >Protected Overrides Function ProcessCmdKey(B yRef msg As
                      >System.Windows .Forms.Message, ByVal keyData As System.Windows. Forms.Keys)
                      >As
                      >Boolean
                      > 'Need to prevent pasting of invalid characters
                      > If keyData = (Keys.Shift Or Keys.Insert) OrElse keyData =
                      >(Keys.Contro l Or Keys.V) Then
                      > Dim data As IDataObject = Clipboard.GetDa taObject
                      > If data Is Nothing Then
                      > Return MyBase.ProcessC mdKey(msg, keyData)
                      > Else
                      > Dim text As String =
                      >CStr(data.GetD ata(DataFormats .StringFormat, True))
                      > If text = String.Empty Then
                      > Return MyBase.ProcessC mdKey(msg, keyData)
                      > Else
                      > For Each ch As Char In text.ToCharArra y
                      > If Not IsValid(ch) Then
                      > Return True
                      > End If
                      > Next
                      > Return MyBase.ProcessC mdKey(msg, keyData)
                      > End If
                      > End If
                      > Else
                      > Return MyBase.ProcessC mdKey(msg, keyData)
                      > End If
                      > End Function
                      >>
                      >Private Function IsValid(ByVal ch As Char) As Boolean
                      > 'TODO: Check if the character is valid
                      >End Function
                      >>
                      >The above will prevent pasting if the text contains any illegal
                      >characters.
                      >>
                      > /claes
                      >>
                      >"Dennis" <Dennis@discuss ions.microsoft. comwrote in message
                      >news:DC67866 7-0480-457C-BF94-F403CC18DC80@mi crosoft.com...
                      Using the KeyPress event does not preclude the user from cutting from
                      some
                      other source and pasting invalid chars into the text box. Use the
                      textbox's
                      "Validating " event to check the text for non-alpha characters.
                      --
                      Dennis in Houston
                      >
                      >
                      "Siva M" wrote:
                      >
                      >There are at least couple of ways to do this: 1. Filtering the
                      >charaters
                      >in
                      >the Keypress event of the textbox itself 2. Using regular expressions
                      >to
                      >find invalid character in the textbox. See which one works ut for
                      >you...
                      >>
                      ><ameen.abdulla h@gmail.comwrot e in message
                      >news:115677791 0.929069.214270 @i42g2000cwa.go oglegroups.com. ..
                      >Hi Guys,
                      >>
                      >I have a textbox in windows form that should only accept alphabets,
                      >numbers, spaces and underscore. If the textbox contains anyother
                      >character it should display a msg at the time of validation.. Is there
                      >any funciton in vb.net for this? or any other way??
                      >>
                      >>
                      >Waiting for ur replies...
                      >>
                      >Thanks in adv.
                      >>
                      >>
                      >>
                      >>
                      >>

                        Comment

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