VB6 equivalent of string.IsNullOrEmpty

Question

I\'m doing some work on a legacy application, and my VB6 skills aren\'t that great. I need to check whether a String field has been initialized and set to something other th

Answer 1

use Is Null for stings or is nothing for objects

use len("string") instead of "string"="" because it is faster

Dim s As String

If Not (s Is Null) Then
  MsgBox "SET"

  if (len(s)>0) then
    MsgBox "size > 0"
  else
    MsgBox "size = 0"
  end if
Else
  MsgBox "not SET"
End If

regards

Answer 2

VB6 was designed to be easy

Use

If str = "" Then 
  ' uninitialised, null or empty ""

• Strings are automatically initialized to [edit] a null string.
• The null string is vbNullString.
• But don't worry about null strings. A VB6 null string is indistinguishable from an empty string "" for (almost) any string manipulation.

Answer 3

I tried, If str = "" Then

but it did not work.

The best way to identify if the given string is null is:

If IsNull(str) Then

' This will work perfectly

Answer 4

'Using VbNullstring can be a very effective way

Dim YourString as string  
dim HasValue as boolean

If YourString = vbnullstring then  
    HasValue = False  
Else  
HasValue = True  
End if

Answer 5

Just adding info to MarkJ's answer. If you are working with a recordset, this

if rs.fields.item("rsField").value = "" then

Will throw a runtime error in case that item is null. You should do this:

if rs.fields.item("rsField").value & "" = "" then

Good luck.

Answer 6

The most optimized and safe way to meet your 3 requirements is as follows:

If LenB(myObj.Str) = 0 
Then Debug.Print "String is empty/null/not initialized" 
Else Debug.Print "Not Empty"