CODEWITHSUNDEEP
vb.net
RossCol
RossCol

Reputation: 1

How can I make InputBox only accept numbers

The code is just asking for the pass rates for 6 different colleges. The rate must be a value between 1 and 100.

I would like it to only allow numbers. I have tried using IsNumeric, but I must not be using it correctly. Here's what I have so far:

For i As Integer = 0 To 5
    passRate(i) = InputBox("Enter the pass rate for " & colleges(i) & " college")
    While passRate(i) > 100 Or passRate(i) < 0
        MsgBox("Error must be a number and be between 0 and 100")
        passRate(i) = InputBox("Enter the pass rate for " & colleges(i) & " college")
    End While
Next i

Upvotes: 0

Views: 9882

Answers (3)

Rick FlyFish
Rick FlyFish

Reputation: 105

 Private Sub txbDwellTime_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txbDwellTime.KeyPress
    pNumDecOnly(e)
    'txbDwellTime.Text = ""
End Sub

Public Sub pNumDecOnly(ByVal e As System.Windows.Forms.KeyPressEventArgs)
    If (Asc(e.KeyChar) >= 48 And Asc(e.KeyChar) <= 57 Or Asc(e.KeyChar) = 46) Then
        'good job do nothing we only allow positive Decimal numbers in this field
        'Asc(e.KeyChar) 48 Through 57 i.e. 0 through 9 Or Asc(e.KeyChar) 46 (dot= .)
    Else
        e.Handled = True
        MsgBox("Only Positive Decimal Numbers Allowed this field")
    End If
End Sub

This will allow only positive Decimal numbers using the ASCII Table, you should be able to modify this for your own use

Upvotes: 0

JStevens
JStevens

Reputation: 2152

I see a couple of things to note.

  1. IsNumeric does not test for just an integer. It will return true for "1.5" since it is numeric. I am assuming that you are looking for an integer value of 1 to 100 as an input result.
  2. An input box returns an string. Some form of parsing (implicit or explicit) must happen if you are going to compare it to an integer type.

To avoid that conversion you could use a simple RegEx. This one will validate it to be an integer between 1 and 100:

Function IsValid(Byval inputString as String) as Boolean
    Dim validValues As New Regex("^[1-9]?[0-9]{1}$|^100$")
    Return validValues.IsMatch(inputString )
End Function

Admitily RegEx can be a bit much... So here is another way to check that the input string will cast to an integer and if so is it between 1 and 100 in value.

Function IsValid(Byval inputString as String) as Boolean
  Dim result As Boolean = False
  Dim inputAsInteger as Integer = 0
  If Integer.TryParse(value, inputAsInteger) Then
     result = inputAsInteger > 0 And inputAsInteger <= 100)
  End If
  Return result
End Function

You can call either of these like so:

   Dim validInput as Boolean = False
   While Not validInput
      validInput = IsValid(InputBox("Enter the pass rate for " & colleges(i) & " college")
   Loop

Upvotes: 0

ashkufaraz
ashkufaraz

Reputation: 5307

use this function for check value

Private Function IsInputNumeric(input As String) As Boolean
        If String.IsNullOrWhiteSpace(input) Then Return False
        If IsNumeric(input) Then Return True
        Dim parts() As String = input.Split("/"c)
        If parts.Length <> 2 Then Return False
        Return IsNumeric(parts(0)) AndAlso IsNumeric(parts(1))
End Function

and use like this 

For i As Integer = 0 To 5

    passRate(i) = InputBox("Enter the pass rate for " & colleges(i) & " college")
    If IsInputNumeric(passRate(i)) Then
        'handle numeric input
    Else
        'handle not a number
    End If
    While passRate(i) > 100 Or passRate(i) < 0
        MsgBox("Error must be a number and be between 0 and 100")
        passRate(i) = InputBox("Enter the pass rate for " & colleges(i) & " college")

    End While

Upvotes: 1

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