unit1.~pas

本光盘是《Delphi 7应用教程》一书的配套光盘

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Label2: TLabel;
    Button1: TButton;
    Label3: TLabel;
    Edit2: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
var
  arr:Array[1..100]of Integer;//定义全局数组变量

procedure pri_num(n:Integer);//自定义过程
var
  m,f,i,j:Integer;   //定义局部变量
begin
  m:=1;
  j:=0;
  Repeat         //给数组赋初值
    arr[m]:=0;
    m:=m+1;
  Until m>100;   //注意不是m>=100
  for m:=3 to (n-1) do //判断小于n的偶数中有多少素数
    begin
      f:=0;
      for i:=2 to trunc(m/2) do
        if ((m mod i)=0) then
          begin
            f:=1;
            break;//能够整除说明不是素数,中断循环
          end;
      if (f=0) then //f=0说明m是素数
        begin
          j:=j+1;
          arr[j]:=m; //将素数m添加到数组中
        end;
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  m,n,k,f:Integer;
begin
  m:=StrToInt(Edit1.Text);
  f:=0;
  pri_num(m);
  for n:=1 to 100 do
    begin
      for k:=1 to 100 do
        if (arr[n]+arr[k]=m) then //寻找符合条件的素数
          begin
            f:=1;
            break; //找到符合条件的素数就不再寻找(中断内循环)
          end;
      if f=1 then
        break; //找到符合条件的素数就中断外循环
    end;
  Edit2.text:=IntToStr(arr[n])+'+'+IntToStr(arr[k]);
end;

end.