OpenOffice.org BASIC Guide - OpenOffice.org wiki

Search and Replace
OpenOffice.org Basic provides the InStr function for searching for a partial string within another string:
ResultString = InStr (MyString, SearchString)
Strings
The SearchString parameter specifies the string to be searched for within MyString. The function returns a
number that contains the position at which the SearchString first appears within MyString; a return value of
zero indicates no match. If you want to find other matches for the string, the function also provides the
opportunity to specify an optional start position from which OpenOffice.org Basic begins the search. In this case,
the syntax of the function is:
ResultString = InStr(StartPosition, MyString, SearchString)
In the previous examples, InStr ignores uppercase and lowercase characters. To change the search so that InStr
is case sensitive, add the parameter 0, as shown in the following example:
ResultString = InStr(MyString, SearchString, 0)
Using the previous functions for editing strings, programmers can search for and replace one string in another
string:
Function Replace(Source As String, Search As String, NewPart As String)
Dim Result As String
Dim StartPos As Long
Dim CurrentPos As Long
Result = ""
StartPos = 1
CurrentPos = 1
If Search = "" Then
Result = Source
Else
Do While CurrentPos 0
CurrentPos = InStr(StartPos, Source, Search)
If CurrentPos 0 Then
Result = Result + Mid(Source, StartPos, _
CurrentPos - StartPos)
Result = Result + NewPart
StartPos = CurrentPos + Len(Search)
Else
Result = Result + Mid(Source, StartPos, Len(Source))
End If ' Position 0
Loop
End If
Replace = Result
End Function
The function searches through the transferred Search string in a loop by means of InStr in the original term
Source. If it finds the search term, it takes the part before the expression and writes it to the Result return
buffer. It adds the NewPart section at the point of the search term Search. If no more matches are found for the
search term, the function establishes the part of the string still remaining and adds this to the return buffer. It
returns the string produced in this way as the result of the replacement process.
Since replacing parts of character sequences is one of the most frequently used functions, the Mid function in
OpenOffice.org Basic has been extended so that this task is performed automatically. The following example
replaces three characters with the string is from the sixth position of the MyString string.
Dim MyString As String
MyString = "This was my text"
Mid(MyString, 6, 3, "is")
Warning – When it is used with 4 arguments, to replace a sub-string in a string, Mid is an instruction, not a
function : it does not return any value !
Chapter 3 · Runtime Library 39