How to find the length without ‘Len’ function?

Without ‘Len’ function, we can find the length of a input by,

E.g.,

 a="tanuj
" b= instrrev(a,"")
 msgbox b

(OR)

str="ABC"
i=1
Do
str1=mid(str,i,1)
If str1<>"" then
      i=i+1
Else
     exit do
End if
loop until str1=""
msgbox i-1