窗体传值中的显示和关闭窗体

 private showInfoMsg form;

  

 if(this.form == null)  //判断是否实例化

 {

     form = new showInfoMsg();

     form.show();

}

 else

{

    if(this.form.IsDisposed) //判断子窗体是否关闭

    {

         from = null;   //如果关闭先释放资源

         form = new showInfoMsg();

         form.show();

    }

    else

    {

          form.Dispose();  //若未关闭传统，就先关闭

          form = null;

          form = new showInfoMsg();

          form.show();

     }

}