unit1.pas

Delphi源码

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Label1: TLabel;
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
var
  p:integer;
  tp:TPoint;
begin
   //是否是0-9，以及是否为+、-号
   if key in ['0'..'9','+','-','.'] then
      begin
         if key in ['+','-'] then
            begin
               p:=pos('+',Edit1.Text)+pos('-',Edit1.Text);
               if p>0 then
                  key:=#0
                  else
                  begin
                    GetCaretPos(tp);
                    if tp.x>1 then
                       key:=#0;
                  end;
            end
            else
              begin
                //判断是否为小数点
                if key='.' Then
                   begin
                     p:=pos('.',Edit1.Text);
                     if p>0 then
                        key:=#0;
                   end;
              end;
      end
      else
        begin
          if key>#31 then
             key:=#0;
        end;
end;


end.