错误消息不适用于文本框值 [英] Error message not working for textbox value

问题描述

我有一个网页表单，上面有三个文本框。前两个做计算，答案进入textbox3。我试图显示一条消息，只有当textbox3中的值为50或更大时才会显示该消息。这是我的代码：

  if （TextBoxHC50.Text <   50 ）
 {
 lblMessage.Text =  你的答案增加了50％以上，; 
} 
  else   if （TextBoxHC50.Text >   50 ）
 {
 
} 

我做错了什么不能正常工作？

解决方案

首先尝试转换你的价值。

  int  iTextBoxValue = Convert.ToInt32（TextBoxHC50.Text）; 
  if （iTextBoxValue <   50 ）{
 lblMessage.Text =  你的答案增加了50％以上，; 
 
}  else   if （iTextBoxValue >   50 ）{
} 

你无法比较一个整数值的字符串，就像你的50一样。（你不应该硬代码立即常量;这对于维护是不好的;更好地声明显式常量，只做一次。）



另外，您没有考虑到文本框输入可能不是表示整数值的有效字符串。假设您要使用 int 类型，请使用 int.TryParse 。您也可以使用 int.Parse ，但随后准备好处理可能的异常。

-SA

I have a web form that has three textboxes on it. The first two do calculation and the answer goes into textbox3. I am trying to display a message that will only display if the value in textbox3 is 50 or greater. Here is my code:

if (TextBoxHC50.Text < 50)
        {
            lblMessage.Text = "Your answer has increased more than 50%,";
        }
        else if (TextBoxHC50.Text > 50)
        {
            
        }

What am I doing wrong for this not to work?

解决方案

Try converting your value first.

int iTextBoxValue = Convert.ToInt32(TextBoxHC50.Text);
if (iTextBoxValue < 50) {
    lblMessage.Text = "Your answer has increased more than 50%,";

} else if (iTextBoxValue > 50) {
}

You cannot compare a string with integer value, like your 50. (You should not also hard-code immediate constants; this is bad for maintenance; better declare explicit constants, do it just once.)

Also, you are not taking into account that the text box input can be not a valid string representing an integer value. Assuming you want to work with the int type, use int.TryParse. You could use int.Parse, too, but then get ready to handle possible exceptions.

—SA

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