delphi-从字符串中去除所有非标准文本字符

// For those who need a disclaimer: 
// This code is meant as a sample to show you how the basic check for non-ASCII characters goes
// It will give low performance with long strings that are called often.
// Use a TStringBuilder, or SetLength & Integer loop index to optimize.
// If you need really optimized code, pass this on to the FastCode people.
function StripNonAsciiExceptCRLF(const Value: AnsiString): AnsiString;
var
  AnsiCh: AnsiChar;
begin
  for AnsiCh in Value do
    if (AnsiCh >= #32) and (AnsiCh <= #127) and (AnsiCh <> #13) and (AnsiCh <> #10) then
      Result := Result + AnsiCh;
end;

function StrippedOfNonAscii(const s: string): string;
var
  i, Count: Integer;
begin
  SetLength(Result, Length(s));
  Count := 0;
  for i := 1 to Length(s) do begin
    if ((s[i] >= #32) and (s[i] <= #127)) or (s[i] in [#10, #13]) then begin
      inc(Count);
      Result[Count] := s[i];
    end;
  end;
  SetLength(Result, Count);
end;

 type CharSet=Set of Char;

 function StripCharsInSet(s:string; c:CharSet):string;
  var i:Integer;
  begin
     result:=\'\';
     for i:=1 to Length(s) do
       if not (s[i] in c) then 
         result:=result+s[i];
  end;  

 s := StripCharsInSet(s,[#0..#9,#11,#12,#14..#31,#127]);

 function StripCharsInSet(s:string; c:CharSet):string;
  var i,j:Integer;
  begin
     SetLength(result,Length(s));
     j:=0;
     for i:=1 to Length(s) do
       if not (s[i] in c) then 
        begin
         inc(j);
         result[j]:=s[i];
        end;
     SetLength(result,j);
  end;  

function StripNonAscii(s:string):string;
var Count, i:Integer;
begin
  Count := 0;
  for i:=1 to Length(s) do
    if ((s[i] >= #32) and (s[i] <= #127)) or (s[i] in [#10, #13]) then
      Inc(Count);
  if Count = Length(s) then
    Result := s // No characters need to be removed, return the original string (no mem allocation!)
  else
    begin
      SetLength(Result, Count);
      Count := 1;
      for i:=1 to Length(s) do
        if ((s[i] >= #32) and (s[i] <= #127)) or (s[i] in [#10, #13]) then
        begin
          Result[Count] := s[i];
          Inc(Count);
        end;
    end;
end;

function StripNonAnsiChars(const AStr: String; const AIgnoreChars: TSysCharSet): string;
var
  lBuilder: TStringBuilder;
  I: Integer;
begin
  lBuilder := TStringBuilder.Create;
  try
    for I := 1 to AStr.Length do
      if CharInSet(AStr[I], [#32..#127] + AIgnoreChars) then
        lBuilder.Append(AStr[I]);
    Result := lBuilder.ToString;
  finally
    FreeAndNil(lBuilder);
  end;
end;

type
  TSBox = array of byte;

function StripNonAscii(buf: array of byte): TSBox;
var temp: TSBox;
    countr, countr2: integer;
const validchars : TSysCharSet = [#32..#127];
begin
if Length(buf) = 0 then exit;
countr2:= 0;
SetLength(temp, Length(buf)); //setze temp auf länge buff
for countr := 0 to Length(buf) do if CharInSet(chr(buf[countr]), validchars) then
  begin
    temp[countr2] := buf[countr];
    inc(countr2); //count valid chars
  end;
SetLength(temp, countr2);
Result := temp;
end;