Convert String.Empty to Nothing/Null

Question

Is there a .Net function that does that. I guess if there isn't i have to make my own method.

The thing is i have a function. It accepts integers. If you pass a 0 integer or a null value it still works. Problem is that the value of an empty textbox is a String.Empty value.

I don't want to use if's. I mean it could but its much nicer if i can just call my function like this

MyFunction(txtTextbox.Text)

But it won't work because it can't convert the string.empty to a integer.

Answer 1

I guess you need:

if(string.IsNullOrEmpty(value)) value = null;

or

int MyFunction(string value)
 {
      if(string.IsNullOrEmpty(value)) return 0;

      int val = 0;
      int.TryParse(value, out val);
      return val;
 }

Answer 2

What about, um, accepting an integer in your function that should read integers, and use int.Parse or int.TryParse on the string beforehand?

Answer 3

Just from a different perspective, I assume that your textbox will also need to allow only numeric to be entered. Otherwise just handling null isnt going to be bullet proof against someone entering non numeric. There must either be some maskings, event handler or validation you have created for it. How about create your own NumTextBox that inherit from TextBox with the input restriction behaviours that you already had and either override Text property or create a new property calls Value which looks after all the conversions and return the appropriate value consistently through out your system.

Answer 4

try this

   Sub MyFunction(ByVal Param1Integer as Integer)
     ' Do Something
   End Sub

   Sub MyFunction(ByVal Param1String as String)
     MyFunction(Val(Param1String))
   End Sub

It assumes that an empty string is the same as 0.

Answer 5

Have you looked into using a NumericUpDown (spin control)? It has a .Value member (always a valid Integer!) instead of having to convert from a String. You can limit the upper and lower values, as well as set a default.

Answer 6

I would just use an inline IF statement (VB):

MyFunction(IIf(txtTextBox.Text Is Nothing, "", txtTextBox.Text))