我一直关注这个tutorial来帮助我创建一个基本的购物篮。尝试使用以下方法运行代码时，应该计算TotalPrice＆amp; OrderForm上篮子的TotalProducts，我得到以下错误：
'System.FormatException'发生在mscorlib.dll中，但未在用户代码中处理。附加信息：输入字符串的格式不正确。
指着
行guideance/suggested在数据库中，ProductPrice的示例是“199.99”，因为本教程仅使用整数，例如“199”。我不确定这是否是造成这个问题的原因？如果是这种情况，下面的代码应该如何修改以包含小数点？
我是编码的新手，所以这真的让我很紧张，我真的很感激一些private void UpdateTotalBill()
{
long TotalPrice = 0;
long TotalProducts = 0;
foreach (DataListItem item in dlBasketItems.Items)
{
//Finds the price label on pnlMyBasket
Label PriceLabel = item.FindControl("lblPrice") as Label;
//Finds the quantity text box on pnlMyBasket
TextBox ProductQuantity = item.FindControl("txtProductQuantity") as TextBox;
long ProductPrice = Convert.ToInt32(PriceLabel.Text) * Convert.ToInt32(ProductQuantity.Text);
TotalPrice = TotalPrice + ProductPrice;
TotalProducts = TotalProducts + Convert.ToInt32(ProductQuantity.Text);
}
txtTotalPrice.Text = Convert.ToString(TotalPrice);
txtTotalProducts.Text = Convert.ToString(TotalProducts);
}
代码更改来克服这个问题
非常感谢你们！
<asp:Panel ID="pnlMyBasket" runat="server" ScrollBars="Auto" Height="500px" BorderColor="Black" BorderStyle="Inset" BorderWidth="1px" Visible="false">
<table align="center" cellspacing="1">
<tr>
<td align="center" class="auto-style4">
<asp:Label ID="lblAvailableStockAlert" runat="server" ForeColor="Red" Font-Bold="true"></asp:Label>
<asp:DataList ID="dlBasketItems" runat="server" RepeatColumns="3" Font-Bold="False"
Font-Italic="False" Font-Overline="False" Font-Strikeout="False" Font-Underline="False"
Width="551px">
<ItemTemplate>
<div align="left">
<table cellspacing="1" style="border: 1px ridge #9900FF; text-align: center; width: 172px;">
<tr>
<td style="border-bottom-style: ridge; border-width: 1px; border-color: #000000">
<asp:Label ID="lblProductName" runat="server" Text='<%# Eval("ProductName")%>' Style="font-weight: 700"></asp:Label>
</td>
</tr>
<tr>
<td>
<img alt="" src='<%# Eval("ProductImageUrl") %>' runat="server" id="imgProductPhoto" style="border: ridge 1px black;
width: 157px; height: 130px;" />
</td>
</tr>
<tr>
<td>AvailableStock: <asp:Label ID="lblAvailableStock" runat="server" Text='<%# Eval("ProductStock") %>'
ToolTip="Available Stock" ForeColor="Red" Font-Bold="true"></asp:Label>
<br />
Price:<asp:Label ID="lblPrice" runat="server" Text='<%# Eval ("ProductPrice") %>'></asp:Label>
<br /> Quantity Required x
<asp:TextBox ID="txtProductQuantity" runat="server" Width="20px" Height="10px" MaxLength="2" OnTextChanged="txtProductQuantity_TextChanged" AutoPostBack="true" ></asp:TextBox>
<asp:HiddenField ID="hfProductID" runat="server" Value='<%# Eval("ProductID") %>' />
</td>
</tr>
<tr>
<td>
<hr /> <asp:Button ID="btnRemoveFromBasket" runat="server" CommandArgument='<%# Eval("ProductID") %>'
Text="Remove From Basket" Width="100%" BorderColor="Black" BorderStyle="Inset" BorderWidth="1px"
OnClick="btnRemoveFromBasket_Click" CausesValidation="false" />
</td>
</tr>
</table>
</div>
</ItemTemplate>
<ItemStyle Width="33%" />
</asp:DataList>
</td>
</tr>
</table>
</asp:Panel>
的 pnlMyBasket
<asp:Panel ID="pnlOrderForm" runat="server" ScrollBars="Auto" Height="500px" BorderColor="Black"
BorderStyle="Inset" BorderWidth="1px" Visible="false">
<table style="width: 258px;">
<tr>
<td align="left">
Name:
</td>
</tr>
<tr>
<td>
<asp:TextBox ID="txtCustomerName" runat="server" Width="231px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtCustomerName"
ErrorMessage="*" ForeColor="Red"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left">
PhoneNo:
</td>
</tr
<tr>
<td>
<asp:TextBox ID="txtCustomerPhoneNo" runat="server" Width="231px" MaxLength="10"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="txtCustomerPhoneNo"
ErrorMessage="*" ForeColor="Red"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left">
EmailID
</td>
</tr>
<tr>
<td>
<asp:TextBox ID="txtCustomerEmailID" runat="server" Width="231px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ControlToValidate="txtCustomerEmailID"
ErrorMessage="*" ForeColor="Red"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left">
Address
</td>
</tr>
<tr>
<td align="left">
<asp:TextBox ID="txtCustomerAddress" runat="server" Width="227px" Height="81px"
TextMode="MultiLine"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" ControlToValidate="txtCustomerAddress"
ErrorMessage="*" ForeColor="Red"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left">
Total Products :
</td>
</tr>
<tr>
<td align="center">
<asp:TextBox ID="txtTotalProducts" runat="server" ReadOnly="True" Width="231px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server" ControlToValidate="txtTotalProducts"
ErrorMessage="*" ForeColor="Red"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left">
Total Price :
</td>
</tr>
<tr>
<td>
<asp:TextBox ID="txtTotalPrice" runat="server" ReadOnly="True" Width="231px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator6" runat="server" ControlToValidate="txtTotalPrice"
ErrorMessage="*" ForeColor="Red"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left">
Payment Mode:
</td>
</tr>
<tr>
<td align="left">
<asp:RadioButtonList ID="rblMethodOfPayment" runat="server">
<asp:ListItem Value="1" Selected="True">1. Collect & Pay In Store</asp:ListItem>
<asp:ListItem Value="2">2. Pay with card</asp:ListItem>
</asp:RadioButtonList>
</td>
</tr>
<tr>
<td>
<br />
</td>
</tr>
<tr>
<td>
<asp:Button ID="btnPlaceOrder" runat="server" OnClick="btnPlaceOrder_Click" Style="font-weight: 700"
Text="PlaceOrder" Width="90px" />
</td>
</tr>
<tr>
<td>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="txtCustomerEmailID"
ErrorMessage="Please Enter Valid EmailId" ForeColor="Red" ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"></asp:RegularExpressionValidator>
</td>
</tr>
</table>
</asp:Panel>
pnlOrderForm
class Sites(models.Model):
site_id = models.AutoField(primary_key=True)
status = models.ForeignKey(Statuses, models.DO_NOTHING, blank=True, null=True)
答案 0 :(得分：0)
您目前正在做的最直接的方式：
var ProductPrice = Convert.ToDecimal(PriceLabel.Text) * Convert.ToDecimal(ProductQuantity.Text);
如果无法将值转换为小数，则会抛出异常。 Decimal.TryParse（）会更好。
https://msdn.microsoft.com/en-us/library/system.decimal.tryparse(v=vs.110).aspx
答案 1 :(得分：0)
我认为您需要转换为十进制，然后转换为long。像这样：
long ProductPrice;
try
{
// hey you never know, someone might just put in an int64 in that textbox!
ProductPrice = Convert.ToInt32(PriceLabel.Text) *
Convert.ToInt32(ProductQuantity.Text);
}
catch
{
decimal tempPrice = Convert.ToDecimal(PriceLabel.Text) *
Convert.ToDecimal(ProductQuantity.Text);
ProductPrice = Convert.ToInt64(tempPrice);
}