Trouble converting a string into double

[davearia]

Hi All,

I have this function as shown below:

Private Function getDimensions(ByVal bigMeasurement As String, ByVal smallMeasurement As String) As Int32
       Dim measurement As Double
       Dim strMeasurement As String
       If smallMeasurement = "0" Then
           measurement = Convert.ToInt32(bigMeasurement)
       Else
           strMeasurement = bigMeasurement + "." + smallMeasurement
           measurement = Convert.ToInt32(strMeasurement)
       End If
       Return measurement
   End Function

When it executes I get an error Input string was not in a correct format.

 

Can anyone please help?

 

Thanks, Dave. :D :D :D

[IngisKahn]

Convert.ToDouble(...) :)

[BlackStone]

First off, integer type values cannot contain decimals, only floating-points can do that (ie: single, double).

Change the return type of the function to Double, and use Convert.ToDouble() instead of Convert.ToInt32().

[davearia]

I apologise for not seeing this myself.

 

But many thanks anyways :D :D :D

[jmcilhinney]

Note that your method should either accept integers or do some error checking. Also, I'd be inclined to use something like:

        Dim measurement As Double

       If Not Double.TryParse("0" & bigMeasurement & "." & smallMeasurement, _
                              Globalization.NumberStyles.AllowDecimalPoint, _
                              Nothing, _
                              measurement) Then
           MessageBox.Show("The measurements need to be integers you idiot!")
       End If

[FYRe]

If you intend to convert a String to an Integer, use the function: "CInt( )"

 

Eg.

 

Assume that a user entered a number '9' into a textbox. Now, that number '9' is a string. If you wish to use the no. '9' for arithmetic calculations; such as add/subtrac/multiply/divide etc, then write this:

 

-----------------------------------------------------------------------------------

 

Dim result As String

 

result = CInt(TextBox1.Text)

' this line converts String '9' to Integer '9' ;assigns the resulting value into "result"

' only when you are using a string (in this case, numbers), for calculation then you'll need to convert into Integer.

 

 

Here are some other conversions:

 

CDbl : Convert to Double

CInt : Convert to Integer

CStr : Convert to String

 

 

-----------------------------------------------------------------------------------

[jmcilhinney]

Assume that a user entered a number '9' into a textbox.

This is exactly why I recommended Double.TryParse, because it is probably not safe to assume that the user has entered a number, unless you have used some validation techniques to restrict input to the TextBox. If you make this assumption and the user enters anything that is not an integer then you'll get an unhandled exception. TryParse attempts to convert a string to a number in the format you specify without throwing an exception if it fails.