使用C#addbutton命令使用asp创建dropdownlist
我正在尝试用asp创建一个下拉列表。一旦用户点击下拉列表,他应该能够选择加号或减号。由于某种原因,代码不起作用。有人能告诉我发生了什么事吗 文本框示例使用C#addbutton命令使用asp创建dropdownlist,c#,asp.net,C#,Asp.net,我正在尝试用asp创建一个下拉列表。一旦用户点击下拉列表,他应该能够选择加号或减号。由于某种原因,代码不起作用。有人能告诉我发生了什么事吗 文本框示例 <script src="Scripts/jquery-1.10.2.js"></script> <script src="Scripts/jquery.validate.min.js"></script> <script src="Scripts/jquery.val
<script src="Scripts/jquery-1.10.2.js"></script>
<script src="Scripts/jquery.validate.min.js"></script>
<script src="Scripts/jquery.validate.js"></script>
<script src="Scripts/jquery.validate.unobtrusive.js"></script>
<script src="Scripts/jquery.validate.unobtrusive.min.js"></script>
<script runat="server">
protected void AddButton_Click(Object sender, EventArgs e)
{
int Answer;
if(DropDownList1.SelectedItem.Text == "+")
{Answer = Convert.ToInt32(Value1.Text) + Convert.ToInt32(Value2.Text);
AnswerMessage.Text = Answer.ToString();}
else if (DropDownList1.SelectedItem.Text == "-")
{
Answer = Convert.ToInt32(Value1.Text) - Convert.ToInt32(Value2.Text);
AnswerMessage.Text = Answer.ToString();
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<h3> TextBox Example </h3>
<p>
<asp:TextBox ID="Value1" Columns="2" MaxLength="3" Text="1" runat="server"/>
+<select id="Select1">
<option></option>
</select>
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem Text="Default text" Value="Default value" />
<asp:ListItem Text="+" > + </asp:ListItem>
<asp:ListItem Text="-" > - </asp:ListItem>
</asp:DropDownList>
<asp:TextBox ID="Value2" Columns="2" MaxLength="3" Text="1" runat="server"/>
=
<asp:Label ID="AnswerMessage" runat="server"/>
</p>
<p>
<asp:Button ID="AddButton" Text="Add" OnClick="AddButton_Click" runat="server"/>
</p>
<p>
<asp:RequiredFieldValidator ID="Value1RequiredValidator" ControlToValidate="Value1"
ErrorMessage="Please enter a value.<br />" Display="Dynamic"
runat="server"/>
<asp:RequiredFieldValidator ID="Value2RequiredValidator" ControlToValidate="Value2"
ErrorMessage="Please enter a value.<br />" Display="Dynamic"
runat="server"/>
<asp:RangeValidator ID="Value1RangeValidator" ControlToValidate="Value1"
Type="Integer" MinimumValue="1" MaximumValue="100" Display="Dynamic"
ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />"
runat="server"/>
<asp:RangeValidator ID="Value2RangeValidator" ControlToValidate="Value2"
Type="Integer" MinimumValue="1" MaximumValue="100" Display="Dynamic"
ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />"
runat="server"/>
</p>
<asp:scriptmanager id="ScriptManager1" runat="server"/>
</form>
</body>
</html>
受保护的void AddButton\u单击(对象发送者,事件参数e)
{
int答案;
如果(DropDownList1.SelectedItem.Text==“+”)
{Answer=Convert.ToInt32(Value1.Text)+Convert.ToInt32(Value2.Text);
AnswerMessage.Text=Answer.ToString();}
else if(DropDownList1.SelectedItem.Text==“-”)
{
答案=Convert.ToInt32(Value1.Text)-Convert.ToInt32(Value2.Text);
AnswerMessage.Text=Answer.ToString();
}
}
文本框示例
+
+
-
=
有两个问题
if语句应该有“==”,也就是说您的if语句应该读为“if(DropDownList1.SelectedItem.Text==”+”),好的,我已经做了更改,但程序仍然无法运行,出于某种原因,代码将无法到达if块的内部。您是否调试并查看了“DropDownList1.SelectedItem.Text”的值?如果是,是什么?
<select id="Select1">
<option></option>
</select>
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem Text="Default text" Value="Default value" />
<asp:ListItem text="+"></asp:ListItem>
<asp:ListItem text ="-"></asp:ListItem>
</asp:DropDownList>