自己写的 限制文本框TEdit中只能输入数字

procedure TForm4.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not (Key in ['0' .. '9', '.', '-', #8, #10, #13]) then
begin
Key := #0;
end else begin
if Key = '-' then
begin
if not string(TEdit(Sender).Text).Contains('-') then
begin
//光标定位在第一个上
TEdit(Sender).SelStart := 0;
end else begin
Key := #0;
end;
end else if Key = '.' then begin
if not string(TEdit(Sender).Text).Contains('.') then
begin
//光标定位在最后一个上
TEdit(Sender).SelStart := Length(TEdit(Sender).Text);
end else begin
Key := #0;
end;
end;
end;
end;

//让 Edit 只接受数字

//方法1：
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not (Key in ['0'..'9']) then
Key := Chr(0);
end;

//方法2：
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not (Byte(Key) in [48..57]) then  // 0的 Ascii 是 48
Key := Chr(0);
end;

//方法3:
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if not CharInSet(Key, ['1'..'5']) then Key := #0;
end;

//Edit 文本的选择与光标位置
procedure TForm1.Button1Click(Sender: TObject);
begin
Edit1.SetFocus;                           //给于焦点
SendMessage(Edit1.Handle,EM_SETSEL,0,1);  //选择第一个字符
SendMessage(Edit1.Handle,EM_SETSEL,0,-1); //全选
SendMessage(Edit1.Handle,EM_SETSEL,1,1);  //光标移到第一个字符后面
SendMessage(Edit1.Handle,EM_SETSEL,0,0);  //光标移到开始
SendMessage(Edit1.Handle,EM_SETSEL,-1,0);  //光标移到开始
end;

//待续...