ASP.NET(C#)数値検証の2つの方法

 
  
int i=0; 
  
if (!int.TryParse(this.txtPage.Text, out i)) 
  
{ 
  
   Response.Write("alert('       ！')"); 
  
   this.txtPage.Text = string.Empty; 
  
 }//        
  
  
 

 
  
try 
  
        { 
   
  
            if (Convert.ToInt32(this.txtPage.Text) > totalPage || Convert.ToInt32(this.txtPage.Text)<1)
            {
                ClientScript.RegisterClientScriptBlock(GetType(), "  ", "alert('       ！')", true);
            }
            else
            {
              ViewState["pageindex"] = this.txtPage.Text;
              GetData();
            }
        }
        catch (Exception)
        {
           ClientScript.RegisterClientScriptBlock(GetType(), "  ", "alert('       ！')", true);
        }