[Lazarus] Checking characters in a string

[silvioprog]

2014-03-12 13:35 GMT-03:00 Howard Page-Clark <hdpc at talktalk.net>:

> If you restrict yourself to Latin ansi encoding and 'number' means a
> numeric digit which does not have to be a whole word, the code is fairly
> simple since almost no parsing is required. Other cases and encodings
> require more complex string parsing. For example:


It is not hard to allow chars like "ã", "Ã", "ñ", "Ñ", "ç", "Ç", "ä", "Ä"
etc. I left the function a little faster too:

// old
function Valid(const s: string): boolean;

  function HasLowerUpperNumeric: boolean;
  var
    c: char;
    lower: boolean = False;
    upper: boolean = False;
    numeric: boolean = False;
  begin
    Result := False;
    for c in s do
    begin
      if c in ['a'..'z'] then
        lower := True
      else if c in ['A'..'Z'] then
        upper := True
      else if c in ['0'..'9'] then
        numeric := True;
      if lower and upper and numeric then
        Exit(True);
    end;
  end;

begin
  if Length(s) < 3 then
    Exit(False);
  Result := HasLowerUpperNumeric;
end;

// new
function ValidPassword(const S: string): Boolean;
var
  P: PChar;
  F: Boolean;
  L: Boolean = False;
  U: Boolean = False;
  N: Boolean = False;
begin
  P := PChar(S);
  while P^ <> #0 do
  begin
    case P^ of
      #48..#57: N := True;
      #65..#90: U := True;
      #97..#122: L := True;
    else
      F := P^ = #195;
      if F then
        case P[1] of
          #128..#159: U := True;
          #160..#191: L := True;
        end;
    end;
    Inc(P);
  end;
  Result := L and U and N;
end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
const
  c = 20000000;
var
  i: integer;
  b, e: TDateTime;
  s: string = 'Ãç1';
  x: Boolean;
begin
  // test Valid efficiency/performance
  b := now;
  for i := 0 to c do
  begin
    x := False;
    x := Valid(s);
  end;
  e := now;
  Edit1.Text := 'Valid: ' + BoolToStr(x, True) + ' - ' +
formatdatetime('hh:nn:ss:zzz', b - e);

  // test ValidPassword efficiency/performance
  b := now;
  for i := 0 to c do
  begin
    x := False;
    x := ValidPassword(s);
  end;
  e := now;
  Edit1.Text := Edit1.Text + ' / ValidPassword: ' + BoolToStr(x, True) + '
- ' + formatdatetime('hh:nn:ss:zzz', b - e);
end;

Result: Valid: *False* - 00:00:00:*861* / ValidPassword: *True* - 00:00:00:
*559*

Sure, it's a function that did just for explain, then it can be easily
improved.

-- 
Silvio Clécio
My public projects - github.com/silvioprog
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