Having been away for few days, I have been fascinated by the thread on the
subject seen as a whole. I may have missed important at the onset, something
like the string is obtained by a ReadControlValue(). If that was true,
then the discussion can go on for a while. But why should it be so? In a
On Wed, 19 May 2004, Jacques Paris wrote:
Make the user be a little bit more responsible for what he enters, and save
the programming for the intelligent parts
He who depends on the user to always do the right thing is going to learn
that his master work of software engineering will not
Spencer,
In terms of speed, I would mostly stick with just the val function. Just
the idea that converting a string to a number and back to a string and
comparing them is fraught with danger, at least for floating point.
Note that the val function returns a number. It returns 0 for things
List,
I just wanted to point out another solution from Bill Thoen that seems
to be pretty bulletproof:
function IsNumeric (byval sVal as string) as logical
dim i as integer
For i = 1 to Len(sVal)
If NOT InStr (1, 0123456789.+-e, mid$(sVal,i,1)) Then
'String contains a
Thanks to all who responded to my question: How can I ensure that a
value entered into an EditText control of a MB dialog is numeric? The
simplest solution was offered by Michael Taylor, Martin Highham, and
Robert Crossley:
If str$(val(teststring)) = teststring then
'numeric
Would that algorithm return the correct result if you fed it a numeric
string like '0023456', or are numbers with leading zeros not going to be
encountered?
On Mon, 17 May 2004, Tim.Nuteson wrote:
Thanks to all who responded to my question: How can I ensure that a
value entered into an
No, it will notThere are a couple of ways to implement them, some of which
are more efficient than others.
The str$(val()) method is the fastest method, but it's not the most robust.
For one thing, it works only for integers. However, it's great for quick
applications that require only
No - str$(val(1.2345)) returns 1.2345.
Where it may fall down, is in the use of thousands separators. For this you
should use
str$(val(DeformatNumber$(10,001))).
With this, it will be robust, but you may want to check for and strip
leading zeroes (as Bill highlights).
Best Regards,
Martin
I'm sorry, but Str$(val())is NOT reliable for testing floating-point values.
I've been burned by this many, many times, and only use str$(val()) to test
integers in very simple applications.
In addition to the issue of leading zeroes, there are also issues with:
1. Looking for a - sign at the
Why don't you try something like this:
Declare Sub Main
Sub Main()
Dim a as string
OnError Goto LocalError
a = a / 1
Exit sub
LocalError:
If Err() = 306 Then
Note a is not numeric
End If
End Sub
- Original Message -
From:
-Original Message-
From: Spencer Simpson [mailto:[EMAIL PROTECTED]
Sent: Monday, May 17, 2004 2:06 PM
To: 'Soporte'
Subject: RE: MI-L Testing to ensure a string is numeric (An unortodox way)
I don't know which version of MapBasic you're using.
In the version I use (5.0) this produces
Listers,
Does anyone have a method using MapBasic to test whether a string is
numeric? I have a dialog with an edittext box that needs a numeric
input. Even if the solution is just a big hack that would be OK, since
I am going to make a logical MB function along the lines of
IsNumeric(123) =
Below is a function that I wrote to get the North/South footage(123) out of a string
with a format of: Fr SE corner 123N 654W.
Function strpnsft(ByVal s1 As String) As integer
Dim fr, n, s, a As Integer
dim s2 as string
s2=ucase$(s1)
fr = InStr(1, s2, FR ) + 5
n = InStr(fr, s2, N) - 1
s =
A quick one would be:
Code...
If IsNumeric(x) Then
do something knowing that it is a number
Else
do something else because it isn't a number
End If
More Code...
Function IsNumeric(ByVal sTestStr as String) As Logical
If Str$(Val(STestStr)) = sTestStr Then
IsNumeric =
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