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VBA - Measuring the length of strings
Start
  Use the Len function to determine the number of characters in a string 
Const baseString As String = "Hello World"

Dim charLength As Long

charLength = Len(baseString)
'charlength = 11
  Use the LenB function to determine the number of bytes in a string 
Const baseString As String = "Hello World"

Dim byteLength As Long

byteLength = LenB(baseString)
'byteLength = 22
  Prefer If Len(myString) = 0 Then over If myString = "" Then

When checking if a string is zero-length, it is better practice, and more efficient, to inspect the length of the string rather than comparing the string to an empty string.

Const myString As String = vbNullString

'Prefer this method when checking if myString is a zero-length string
If Len(myString) = 0 Then
    Debug.Print "myString is zero-length"
End If

'Avoid using this method when checking if myString is a zero-length string
If myString = vbNullString Then
    Debug.Print "myString is zero-length"
End If

Remarks

A string's length can be measured in two ways: The most frequently used measure of length is the number of characters using the Len functions, but VBA can also reveal the number of bytes using LenB functions. A double-byte or Unicode character is more than one byte long.

 

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