Code:
function Between(const s1, s2, s: string): string;
var
  p1, p2: Integer;
begin
  Result := '';
  p1 := Pos(s1, s);
  p2 := PosEx(s2, s, Max(1, p1));
  if (p1 > 0) and (p2 > 0) then
    Result := Copy(s, p1 + Length(s1), p2 - p1 - Length(s1));
end;

function Explode(Sep, s: string): array of String;
var
  p1, p2: Integer;
begin
  SetLength(Result, 0);
  s := s + Sep;
  p1 := 1;
  p2 := Pos(Sep, s);
  while (p1 > 0) and (p2 > 0) do
  begin
    SetLength(Result, Length(Result) + 1);
    Result[High(Result)] := Copy(s, p1, p2 - p1);
    p1 := p2 + Length(Sep);
    p2 := PosEx(Sep, s, p1 + 1);
  end;
end;

function GetLetters(const s: string): string;
var
  i: Integer;
begin
  Result := '';
  for i := 1 to Length(s) do
    if CharInSet(s[i], ['a'..'z', 'A'..'Z']) then
      Result := Result + s[i];
end;

function TrimNumbers(const s: string): string;
var
  i: Integer;
begin
  Result := '';
  for i := 1 to Length(s) do
    if (not CharInSet(s[i], ['0'..'9'])) then
      Result := Result + s[i];
end;
Its basicly the same in almost every language, some languages like java even have them done for you already

Ill post more later, if there is interest..I can help you convert them also