unit1.pas

一个截取字符串的小例子

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Edit4: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Edit4KeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
function getstr(Ystr,Mstr:string;istar:byte):string; //从字符串中截取字符串
var s:string;
i:byte;
begin
result:='';
i:=0;
for i:=0 to length(Ystr) do
    if i<istar then
    delete(Ystr,1,pos(Mstr,Ystr)) else
    break;
s:=copy(Ystr,i-strtoint(form1.edit4.text)-1,pos(Mstr,Ystr)-1);
delete(s,1,length(Mstr)-1);
if s<>'' then
result:=s else
result:='提取串为空串！'
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
edit2.Text:=getstr(edit1.Text,edit3.text,strtoint(edit4.text));
end;

procedure TForm1.Edit4KeyPress(Sender: TObject; var Key: Char);
begin
if (Key < '0') or (Key > '9') 
then Key := Chr(0);
end;

end.