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   ► KBProgrammingVB Classic   Print This     
  From the April 2015 Issue of Prestwood eMag
 
VB Classic Empty String Check (Len(s&vbNullString))
 
Posted 11 years ago on 9/17/2009
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KB102040

Languages Focus: Empty String Check

An empty string is a zero length string, a string that is equal to null (""), or not assigned. In some languages, you can check if a string is empty by comparing it to an empty string (""). Some languages distinguish between nil and null ("") so checking if the length is 0 is easier.

VB Classic Empty String Check

In VB Classic, you have to add an empty string to the value being compared in order to get consistent results. For example, add &"" to your string varilable or it's code equivalent &vbNullString. Then compare to an empty string or verify it's length to 0 with Len.

Syntax Example:

All these will work for variables unassigned, set to "", or set to Null:

If s&"" = "" Then
MsgBox ("Quotes with &'' say null is empty")
End If
 
If Len(s&"") = 0 Then
MsgBox ("Len with &'' says null is empty")
End If
 
If Len(s&vbNullString) = 0 Then
MsgBox ("Using vbNullString also works!")
End If

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Code Contributed By Mike Prestwood:

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