单精度格式化函数

//1.定义变量
Temp_F: real = 113.05;

//2.执行函数
procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit1.text :=FormatFloat('0.0',Temp_F);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Edit2.text :=FormatCurr('0.0',Temp_F);
end;

procedure TForm1.Button3Click(Sender: TObject);
  function RoundFloat(f:double;i:integer):double;
  var
    s:string;
    ef:extended;
  begin
    s:='#.'+StringOfChar('0',i);
    ef:=StrToFloat(FloatToStr(f));//防止浮点运算的误差
    result:=StrToFloat(FormatFloat(s,ef));
  end;
begin
  Edit3.text :=FloattoStr(RoundFloat(Temp_F,2));
end;

procedure TForm1.Button4Click(Sender: TObject);
  function MyRound(s:real;non:integer):real;
  var
    roundi:integer;
    j:double;
  begin
    j:=s;
    for roundi:=10 downto non do
    begin
     j:=j+1/power(10,roundi+2);
     j:=roundto(j,-roundi);
    end;
    result:=j;
  end;
begin
  Edit4.text :=FloattoStr(MyRound(Temp_F,3));
end;

procedure TForm1.Button5Click(Sender: TObject);
  Function FRoundInt64(x:Extended):Int64;
  var
    Temp:Extended;
  begin
    Temp:=Frac(x);
    if temp=0.5 then
      Result:=Trunc(x)+1
    else
      Result:=Trunc(x);
  end;
begin
  Edit5.text :=FloattoStr(FRoundInt64(Temp_F));
end;

procedure TForm1.Button6Click(Sender: TObject);
  function DoRound(Value: Extended): Int64;
  procedure Set8087CW(NewCW: Word);
  asm
    MOV     Default8087CW,AX
    FNCLEX
    FLDCW   Default8087CW
  end;
  const
    RoundUpCW         = $1B32;
  var
    OldCW             : Word;
  begin
    OldCW := Default8087CW;
    try
      Set8087CW(RoundUpCW);
      Result := Round(Value);
    finally
      Set8087CW(OldCW);
    end;
  end;
begin
  Edit6.text :=FloattoStr(DoRound(Temp_F));
end;

procedure TForm1.Button7Click(Sender: TObject);
  const
    defDoubleEpsilon      = 1E-12;
  function FRound(F: Double; ADecimal: Integer; AEpsilon: Double = defDoubleEpsilon): Double;
  const
    CDecBase: array[0..9] of Double = (
      1, 1E1, 1E2, 1E3, 1E4, 1E5, 1E6, 1E7, 1E8, 1E9);
  var
    P: Int64 absolute F;
    IntVal, DecimalVal, ModVal: Int64;
  begin
    if ADecimal < 0 then
    begin
      IntVal := Trunc(F);
      ADecimal := Abs(ADecimal);
      if ADecimal > 9 then
        raise Exception.CreateFmt('Not Support Param -%d.', [ADecimal]);
      IntVal := IntVal div Trunc(CDecBase[ADecimal - 1]);
      ModVal := IntVal mod 10;
      IntVal := IntVal div 10;
      if ModVal >= 5 then
        Inc(IntVal, 1)
      else if ModVal <= -5 then
        Inc(IntVal, -1);
      Result := IntVal * CDecBase[ADecimal];
    end
    else if ADecimal <= 8 then
    begin
      Inc(P, 512); // 可保留14位有效数字(13位准确,最后一位可能差1)
      IntVal := Trunc(F);
      DecimalVal := Trunc(Frac(F) * CDecBase[ADecimal + 1]);
      ModVal := DecimalVal mod 10;
      if ModVal >= 5 then
        Inc(DecimalVal, 10)
      else if ModVal <= -5 then
        Inc(DecimalVal, -10);
      Result := IntVal + (DecimalVal div 10) / CDecBase[ADecimal];
    end
    else begin
      Result := StrToFloat(FormatFloat('0.' + StringOfChar('#', ADecimal), F + AEpsilon));
      if SameValue(Result, 0.0) then Result := 0;
    end;
  end;
begin
  Edit7.text :=FloattoStr(FRound(Temp_F,3));
end;