Author: Jonas Bilinkevicius

How to search and replace strings in a TMemo

Answer:

Doing search and replace on strings has been made trivial because of these 3 
functions: Pos(), Delete(), and Insert(). Pos() takes two parameters, a pattern 
search string, and a string to find the pattern in - it returns the location of the 
string, or 0 if it does not exist. Delete() takes three parameters, the string to 
delete from, location of where to start deleting, and how much to delete. 
Similarly, Insert() takes three parameters too. The string that will be inserted, 
the string to insert into, the location to insert.

Many class properties use strings to store values, so one can use this method on 
any of them. For instance, the searching and replacing of an entire TMemo component 
might look like this:

1   procedure TForm1.Button2Click(Sender: TObject);
2   var
3     i: integer;
4     s1: string;
5     SearchStr: string;
6     NewStr: string;
7     place: integer;
8   begin
9     SearchStr := 'line';
10    NewStr := 'OneEye';
11    for i := 0 to Memo1.Lines.Count - 1 do
12    begin
13      s1 := Memo1.Lines[i];
14      repeat
15        Place := pos(SearchStr, s1);
16        if place > 0 then
17        begin
18          Delete(s1, Place, Length(SearchStr));
19          Insert(NewStr, s1, Place);
20          Memo1.Lines[i] := s1;
21        end;
22      until
23        place = 0;
24    end;
25  end;