Excel: last character/string match in a string

How about creating a custom function and using that in your formula? VBA has a built-in function, InStrRev, that does exactly what you're looking for.

Put this in a new module:

Function RSearch(str As String, find As String)
    RSearch = InStrRev(str, find)
End Function

And your function will look like this (assuming the original string is in B1):

=LEFT(B1,RSearch(B1,"\"))

tigeravatar and Jean-François Corbett suggested to use this formula to generate the string right of the last occurrence of the "\" character

=TRIM(RIGHT(SUBSTITUTE(A1,"\",REPT(" ",LEN(A1))),LEN(A1)))

If the character used as separator is space, " ", then the formula has to be changed to:

=SUBSTITUTE(RIGHT(SUBSTITUTE(A1," ",REPT("{",LEN(A1))),LEN(A1)),"{","")

No need to mention, the "{" character can be replaced with any character that would not "normally" occur in the text to process.

Just came up with this solution, no VBA needed;

Find the last occurance of "_" in my example;

=IFERROR(FIND(CHAR(1);SUBSTITUTE(A1;"_";CHAR(1);LEN(A1)-LEN(SUBSTITUTE(A1;"_";"")));0)

Explained inside out;

SUBSTITUTE(A1;"_";"") => replace "_" by spaces
LEN( *above* ) => count the chars
LEN(A1)- *above*  => indicates amount of chars replaced (= occurrences of "_")
SUBSTITUTE(A1;"_";CHAR(1); *above* ) => replace the Nth occurence of "_" by CHAR(1) (Nth = amount of chars replaced = the last one)
FIND(CHAR(1); *above* ) => Find the CHAR(1), being the last (replaced) occurance of "_" in our case
IFERROR( *above* ;"0") => in case no chars were found, return "0"

Hope this was helpful.

You could use this function I created to find the last instance of a string within a string.

Sure the accepted Excel formula works, but it's much too difficult to read and use. At some point you have to break out into smaller chunks so it's maintainable. My function below is readable, but that's irrelevant because you call it in a formula using named parameters. This makes using it simple.

Public Function FindLastCharOccurence(fromText As String, searchChar As String) As Integer
Dim lastOccur As Integer
lastOccur = -1
Dim i As Integer
i = 0
For i = Len(fromText) To 1 Step -1
    If Mid(fromText, i, 1) = searchChar Then
        lastOccur = i
        Exit For
    End If
Next i

FindLastCharOccurence = lastOccur
End Function

I use it like this:

=RIGHT(A2, LEN(A2) - FindLastCharOccurence(A2, "\"))

Considering a part of a Comment made by @SSilk my end goal has really been to get everything to the right of that last occurence an alternative approach with a very simple formula is to copy a column (say A) of strings and on the copy (say ColumnB) apply Find and Replace. For instance taking the example: Drive:\Folder\SubFolder\Filename.ext

This returns what remains (here Filename.ext) after the last instance of whatever character is chosen (here \) which is sometimes the objective anyway and facilitates finding the position of the last such character with a short formula such as:

=FIND(B1,A1)-1