How-to-replace-occurences-of-a-substring-in-a-string


            Title: How to replace occurences of a substring in a string
procedure TForm1.Button1Click(Sender: TObject);
var
 sNewText: string;
begin
 // Replace the first Word "FOX" with "tiger".
 
 sNewText := StringReplace('The quick brown fox jumps over the lazy fox.',
 'FOX', 'tiger', [rfIgnoreCase]);
 ShowMessage(sNewText);
 // Remove all Spaces in a string.
 
 sNewText := StringReplace('This is a Text with Spaces', ' ', '', [rfReplaceAll]);
 ShowMessage(sNewText);
 // Replace all "True" in a Memo with "False".
 
 Memo1.Text := StringReplace(Memo1.Text, 'True', 'False', [rfReplaceAll, rfIgnoreCase]]);
end;
{2.}
{
 StringReplace is not available for D3/D2/D1 users.
 Use the slightly modified StringReplace below.
 (from sysutils.pas but without ANSI support)
}
type
 TReplaceFlags = set of (rfReplaceAll, rfIgnoreCase);
function StringReplace(const S, OldPattern, NewPattern: string;
 Flags: TReplaceFlags): string;
var
 SearchStr, Patt, NewStr: string;
 Offset: Integer;
begin
 if rfIgnoreCase in Flags then
 begin
 SearchStr := UpperCase(S);
 Patt := UpperCase(OldPattern);
 end
 else
 begin
 SearchStr := S;
 Patt := OldPattern;
 end;
 NewStr := S;
 Result := '';
 while SearchStr '' do
 begin
 Offset := Pos(Patt, SearchStr);
 if Offset = 0 then
 begin
 Result := Result + NewStr;
 Break;
 end;
 Result := Result + Copy(NewStr, 1, Offset - 1) + NewPattern;
 NewStr := Copy(NewStr, Offset + Length(OldPattern), MaxInt);
 if not (rfReplaceAll in Flags) then
 begin
 Result := Result + NewStr;
 Break;
 end;
 SearchStr := Copy(SearchStr, Offset + Length(Patt), MaxInt);
 end;
end;
{3.}
 
 Replace all OldSubStr in S with NewSubStr.
}
function ReplaceStr(s, OldSubStr, NewSubStr: string): string;
var
 i: integer;
 OldSubLen, TotalLength: integer;
begin
 Result := '';
 if s '' then
 begin
 OldSubLen := Length(OldSubStr); // f¨¹r die Performance - for performance
 TotalLength := Length(s);
 i := 1;
 while i = TotalLength do
 begin
 if (i = TotalLength - OldSubLen) and (Copy(s, i, OldSubLen) = OldSubStr) then
 begin
 Result := Result + NewSubStr;
 Inc(i, OldSubLen);
 end
 else
 begin
 Result := Result + s[i];
 Inc(i);
 end;
 end;
 end;
end;
String Delphi
