Integer.TryParse - a better way?

Question

I find myself often needing to use Integer.TryParse to test if a value is an integer. However, when you use TryParse, you have to pass a reference variable to the function, so I find myself always needing to create a blank integer to pass in. Usually it looks something like:

Dim tempInt as Integer
If Integer.TryParse(myInt, tempInt) Then

I find this to be quite cumbersome considering that all I want is a simple True / False response. Is there a better way to approach this? Why isn't there an overloaded function where I can just pass the value I want to test and get a true / false response?

Answer 1

No need to declare the integer.

If Integer.TryParse(intToCheck, 0) Then

or

If Integer.TryParse(intToCheck, Nothing) Then

---

If you have .Net 3.5 ability you can create an extension method for strings.

Public Module MyExtensions

    <System.Runtime.CompilerServices.Extension()> _
    Public Function IsInteger(ByVal value As String) As Boolean
        If String.IsNullOrEmpty(value) Then
            Return False
        Else
            Return Integer.TryParse(value, Nothing)
        End If
    End Function

End Module

And then call like:

If value.IsInteger() Then

---

Sorry, getting carried away I know, but also you can add this to the MyExtensions class above in .Net 3.5 and not worry unless you need validations.

<System.Runtime.CompilerServices.Extension()> _
Public Function ToInteger(ByVal value As String) As Integer
    If value.IsInteger() Then
        Return Integer.Parse(value)
    Else
        Return 0
    End If
End Function

Then simply use

value.ToInteger()

This will return 0 if it isn't a valid Integer.

Answer 2

Since you are using VB.net you can use the IsNumeric Function

If IsNumeric(myInt) Then
    'Do Suff here
End If

Answer 3

public static class Util {

    public static Int32? ParseInt32(this string text) {
        Int32 result;
        if(!Int32.TryParse(text, out result))
            return null;
        return result;
    }

    public static bool IsParseInt32(this string text) {
        return text.ParseInt32() != null;
    }

}

Answer 4

Try this code.

Module IntegerHelpers

  Function IsInteger(ByVal p1 as String) as Boolean
    Dim unused as Integer = 0
    return Integer.TryParse(p1,unused)
  End Function
End Module

The nice part is that since it's declared as a Module level function it can be used without a qualifier. Example Usage

return IsInteger(mInt)

Answer 5

Why not write an extension method to clean up your code? I haven't written VB.Net for a while, but here is an example in c#:

public static class MyIntExtensionClass
{
  public static bool IsInteger(this string value)
  {
    if(string.IsNullOrEmpty(value))
      return false;

    int dummy;
    return int.TryParse(value, dummy);
  }
}

Answer 6

A variation would be:

Int32.TryParse(input_string, Globalization.NumberStyles.Integer)

Answer 7

J Ambrose Little performed timing tests for IsNumeric checks back in 2003. You may wish to retry the mentioned tests with v2 of the CLR.