unit3.~pas

计算个人所得税与牛顿迭代法实现的作业源码。

unit Unit3;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm3 = class(TForm)
    Button1: TButton;
    Edit2: TEdit;
    Panel2: TPanel;
    Edit1: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form3: TForm3;

implementation

{$R *.dfm}

procedure TForm3.Button1Click(Sender: TObject);
var
  s1,s2,s3,s4,s5,s6,s7,s8:real;
  s,n:real;

begin
  n:=strtofloat(Edit1.Text);
  if n<800 then
    messagedlg('不超过800元，不用纳税!',mterror,[mbyes],0)
  else
    begin
      s1:=500*0.05;
      s2:=2000*0.10;
      s3:=5000*0.15;
      s4:=20000*0.20;
      s5:=40000*0.25;
      s6:=60000*0.30;
      s7:=80000*0.35;
      s8:=100000*0.40;
      n:=n-800;

      if n<500 then s:=n*0.05
      else
        if n<2000then s:=(n-500)*0.10+s1
        else
          if n<5000 then s:=(n-2000)*0.15+s2
          else
            if n<20000 then s:=(n-5000)*0.2+s3
            else
              if n<40000 then s:=(n-20000)*0.25+s4
              else
                if n<60000 then s:=(n-40000)*0.3+s5
                else
                  if n<80000 then s:=(n-60000)*0.35+s6
                  else
                    if n<100000 then s:=(n-80000)*0.4+s7
                    else s:=(n-100000)*0.45+s8;

     Edit2.Text:=format('%f 元',[s]);
    end;
  Edit1.SelectAll;


end;

procedure TForm3.Edit1KeyPress(Sender: TObject; var Key: Char);

var l:boolean;
begin
  l:=(key<#8)or(key>#8)and(key<=#45)or(key>#46)and(key<#48)or(key>#57);
  if l then
    begin
      key:=#0;
      messagedlg('不能输入非法字符，请重新输入!',mterror,[mbyes],0);

    end;
end;

end.