Remove last n characters of string after the dot with Autohotkey - autohotkey

Question

I am using Autohotkey.
I have a string that looks like this S523.WW.E.SIMA. I want to remove the last few characters of the string after the dot (including the dot itself). So, after the removal, the string will look like S523.WW.E.
This may look like a simple question but I just cannot figure out using the available string functions in Autohotkey. How can this be done using Autohotkey? Thank you very much.

Answer 1

Example 1 (last index of)
string := "S523.WW.E.SIMA"
LastDotPos := InStr(string,".",0,0) ; get position of last occurrence of "."
result := SubStr(string,1,LastDotPos-1) ; get substring from start to last dot
MsgBox %result% ; display result
See InStr
See SubStr
Example 2 (StrSplit)
; Split it into the dot-separated parts,
; then join them again excluding the last part
parts := StrSplit(string, ".")
result := ""
Loop % parts.MaxIndex() - 1
{
if(StrLen(result)) {
result .= "."
}
result .= parts[A_Index]
}
Example 3 (RegExMatch)
; Extract everything up until the last dot
RegExMatch(string, "(.*)\.", result)
msgbox % result1
Example 4 (RegExReplace)
; RegExReplace to remove everything, starting with the last dot
result := RegExReplace(string, "\.[^\.]+$", "")