1 //1.定义变量  2 Temp_F: real = 113.05;  3   4 //2.执行函数  5 procedure TForm1.Button1Click(Sender: TObject);  6 begin  7   Edit1.text :=FormatFloat('0.0',Temp_F);  8 end;  9  10 procedure TForm1.Button2Click(Sender: TObject); 11 begin 12   Edit2.text :=FormatCurr('0.0',Temp_F); 13 end; 14  15 procedure TForm1.Button3Click(Sender: TObject); 16   function RoundFloat(f:double;i:integer):double; 17   var 18     s:string; 19     ef:extended; 20   begin 21     s:='#.'+StringOfChar('0',i); 22     ef:=StrToFloat(FloatToStr(f));//防止浮点运算的误差 23     result:=StrToFloat(FormatFloat(s,ef)); 24   end; 25 begin 26   Edit3.text :=FloattoStr(RoundFloat(Temp_F,2)); 27 end; 28  29 procedure TForm1.Button4Click(Sender: TObject); 30   function MyRound(s:real;non:integer):real; 31   var 32     roundi:integer; 33     j:double; 34   begin 35     j:=s; 36     for roundi:=10 downto non do 37     begin 38      j:=j+1/power(10,roundi+2); 39      j:=roundto(j,-roundi); 40     end; 41     result:=j; 42   end; 43 begin 44   Edit4.text :=FloattoStr(MyRound(Temp_F,3)); 45 end; 46  47 procedure TForm1.Button5Click(Sender: TObject); 48   Function FRoundInt64(x:Extended):Int64; 49   var 50     Temp:Extended; 51   begin 52     Temp:=Frac(x); 53     if temp=0.5 then 54       Result:=Trunc(x)+1 55     else 56       Result:=Trunc(x); 57   end; 58 begin 59   Edit5.text :=FloattoStr(FRoundInt64(Temp_F)); 60 end; 61  62 procedure TForm1.Button6Click(Sender: TObject); 63   function DoRound(Value: Extended): Int64; 64   procedure Set8087CW(NewCW: Word); 65   asm 66     MOV     Default8087CW,AX 67     FNCLEX 68     FLDCW   Default8087CW 69   end; 70   const 71     RoundUpCW         = $1B32; 72   var 73     OldCW             : Word; 74   begin 75     OldCW := Default8087CW; 76     try 77       Set8087CW(RoundUpCW); 78       Result := Round(Value); 79     finally 80       Set8087CW(OldCW); 81     end; 82   end; 83 begin 84   Edit6.text :=FloattoStr(DoRound(Temp_F)); 85 end; 86  87 procedure TForm1.Button7Click(Sender: TObject); 88   const 89     defDoubleEpsilon      = 1E-12; 90   function FRound(F: Double; ADecimal: Integer; AEpsilon: Double = defDoubleEpsilon): Double; 91   const 92     CDecBase: array[0..9] of Double = ( 93       1, 1E1, 1E2, 1E3, 1E4, 1E5, 1E6, 1E7, 1E8, 1E9); 94   var 95     P: Int64 absolute F; 96     IntVal, DecimalVal, ModVal: Int64; 97   begin 98     if ADecimal < 0 then 99     begin100       IntVal := Trunc(F);101       ADecimal := Abs(ADecimal);102       if ADecimal > 9 then103         raise Exception.CreateFmt('Not Support Param -%d.', [ADecimal]);104       IntVal := IntVal div Trunc(CDecBase[ADecimal - 1]);105       ModVal := IntVal mod 10;106       IntVal := IntVal div 10;107       if ModVal >= 5 then108         Inc(IntVal, 1)109       else if ModVal <= -5 then110         Inc(IntVal, -1);111       Result := IntVal * CDecBase[ADecimal];112     end113     else if ADecimal <= 8 then114     begin115       Inc(P, 512); // 可保留14位有效数字(13位准确,最后一位可能差1)116       IntVal := Trunc(F);117       DecimalVal := Trunc(Frac(F) * CDecBase[ADecimal + 1]);118       ModVal := DecimalVal mod 10;119       if ModVal >= 5 then120         Inc(DecimalVal, 10)121       else if ModVal <= -5 then122         Inc(DecimalVal, -10);123       Result := IntVal + (DecimalVal div 10) / CDecBase[ADecimal];124     end125     else begin126       Result := StrToFloat(FormatFloat('0.' + StringOfChar('#', ADecimal), F + AEpsilon));127       if SameValue(Result, 0.0) then Result := 0;128     end;129   end;130 begin131   Edit7.text :=FloattoStr(FRound(Temp_F,3));132 end;