VBA Function InStr

Instr function is to get the position of the first occurrence of one string within another. The search String is from left  to right inside another String to get the position for example we wish to get the position of back slash "\" from path "C:\Users\UserName\Desktop\MyBook.xlsx", if start from 1 then the position of back slash is 3 but if we start from 5 then the position is 9.

Syntax : InStr(Start,String1,String2,Compare Value) , Returns : Long

Constant	Value	Description
vbUseCompareOption	-1	Performs a comparison by using the setting of the Option Compare statement.
vbBinaryCompare	0	Performs a binary comparison.
vbTextCompare	1	Performs a textual comparison.
vbDatabaseCompare	2	Microsoft Access only. Performs a comparison based on information in your database.

Normally for Compare Value we use 0 (case sensitive and default) or 1.Usually we omitted this value to let default which is equal to 0 (binary comparison). For more clear explanation refer below picture.

VBA Vode: (Example to get Postion of Back slash \)

Option Explicit
Sub Examples_InStr()
    Dim StrLink As String
    StrLink = "C:\Users\UserName\Desktop\MyBook.xlsx"
    
    'To Get C:\ from above string
    Debug.Print Left(StrLink, InStr(1, StrLink, "\", 1))
    
    'To Get xlsx from above string
    Debug.Print Right(StrLink, Len(StrLink) - InStr(1, StrLink, ".", 1))
End Sub

VBA Vode: (Example to check existance of Name keyword)

Option Explicit
Sub Examples_InStrTest()
    Dim StrLink As String
    Dim iPos As Long
    
    StrLink = "C:\Users\UserName\Desktop\MyBook.xlsx"
    iPos = InStr(1, StrLink, "Name")
    If iPos = 0 Then
        MsgBox "Keyword Name not found."
    Else
        MsgBox "Keyword Name found Start at= " & iPos
    End If
End Sub

Note:
Usually we use InStr Function combine with other functions like Left,Right,Mid,Len and etc.

Read more about Instr function, excelmacros, macro excel,
excel programming, excel vba at below links.

Microsoft Reference-Instr-function
Other Reference-Instr-function.htm

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