function to check if a string is a number

[shresthaal]

is there a function in the vb.net library which can tell if a string is a number or not

eg.
dim A as string
A = "11"

the function should return true for A = "11" and false for A = "12a"

 

[ca8msm]

There's the old IsNumeric function from the VisualBasic class


____________________________________________________________

Need help finding an answer?

Try the Search Facility or read FAQ222-2244 on how to get better results.

 

[earthandfire]

dim a as string
a = "11"
if IsNumeric(a) then
messagebox.show("yes")
else
messagebox.show("no")
end if


Hope this helps.

 

[TipGiver]

or

use a Regular Expression.

RESOURCES:

http://www.regexbuddy.com/create.html

 

[RoyVidar]

Stealing" earthandfire's suggestion, do also try with "numbers" like this:

[tt]dim a as string
a = "1E1" ' <- note the letter E ("Scientific" notation)
if IsNumeric(a) then
messagebox.show("yes")
else
messagebox.show("no")
end if[/tt]

If the above scenario is a possibility, then I'd suggest other approaches than IsNumeric. Combine IsNumeric with looping the string, Regex ... Here's one thread with some discussions and suggestions thread796-1104616

(here's discussion from the VB5/6 forum with some history too, should it be interesting thread222-1071392)

Here's an attempt that might work, if the string must contain only digits.

[tt] Dim strNum As String = "234E34"
Dim lngCount As Long
Dim lngLen As Long = strNum.Length - 1

For lngCount = 0 To lngLen
If (Not Char.IsDigit(strNum, lngCount)) Then
MessageBox.Show("contains text")
End If
Next lngCount[/tt]

Roy-Vidar

 

[Tranman]

Private Function Parser(byVal str as String) as Boolean
Try
Double.Parse(str)
Return True
Catch fe as FormatException
Return False
End Try
End Function

Works with scientific notation as well as regular numbers.

Tranman


"Adam was not alone in the Garden of Eden, however,...much is due to Eve, the first woman, and Satan, the first consultant." Mark Twain