Mega Code Archive
How to replace occurences of a substring in a string
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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;
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