尝试将类型'double'转换为'int'时出现问题 [英] Problem trying to convert type 'double' to 'int'

问题描述

 private Product CreateProduct（）
 {
 Product product = new Product（）; 
 
 product.Name = txtName.Text; 
 product.Price =  Convert.ToDouble（txtPrice.Text）;  
 product.TypeID = Convert.ToInt32（ddlType.SelectedValue）; 
 product.Description = txtDescription.Text; 
 product.Image = ddlImage.SelectedValue; 
 
退货产品; 
} 

我的尝试：



我试过Convert.ToInt32（txtPrice.Text）;,但是这不起作用

解决方案

试试：

  double 价格; 
  if （！double.TryParse（txtPrice.Text， out  price））
 {
  //  向用户报告输入问题。 
 ... 
  return ; 
} 
 product.Price = price; 

如果Price是一个整数 - 它可能不应该是 - 那么试试：

  double 价格; 
  if （！double.TryParse（txtPrice.Text， out  price））
 {
  //  向用户报告输入问题。 
 ... 
  return ; 
} 
 product.Price =（ int ）价格; 

永远不要使用Convert.To ...来处理用户输入：它总是在坏值上抛出异常，用户总是会犯错误。如果您填写了包含大量数据的表单，那么应用程序会因为您键入，而不是。而崩溃。你会非常恼火 - 所以让用户犯错并让他们纠正错误！

嗯。我一直在想，因为文本框名称是txtPrice，我想知道该框是否持有货币格式的字符串（£12.30）。如果是这种情况，请尝试按照以下示例

 System.Globalization.CultureInfo provider =  new  System.Globalization.CultureInfo（  en-GB）; 
  string  txtPrice =  £12.30< /跨度>; 
  double 价格; 
  double  .TryParse（txtPrice，System.Globalization.NumberStyles.AllowThousands | 
 System.Globalization.NumberStyles.AllowDecimalPoint | 
 System。 Globalization.NumberStyles.AllowCurrencySymbol，provider， out  price）; 
 product.Price = price; 

输出：12.3

如果价格是整数

< pre lang =c＃> product.Price =（ int ）价格;

输出：12

private Product CreateProduct()
    {
        Product product = new Product();

        product.Name = txtName.Text;
        product.Price = Convert.ToDouble(txtPrice.Text);
        product.TypeID = Convert.ToInt32(ddlType.SelectedValue);
        product.Description = txtDescription.Text;
        product.Image = ddlImage.SelectedValue;

        return product;
    }

What I have tried:

I've tried Convert.ToInt32(txtPrice.Text);, but that doesnt work either

解决方案

Try:

double price;
if (!double.TryParse(txtPrice.Text, out price))
   {
   // Report input problem to user.
   ...
   return;
   }
product.Price = price;

If Price is an integer - and it probably shouldn't be - then try:

double price;
if (!double.TryParse(txtPrice.Text, out price))
   {
   // Report input problem to user.
   ...
   return;
   }
product.Price = (int) price;

Never use Convert.To... to handle user input: it always throws an exception on bad values, and users make mistakes all the time. If you had filled out a form with a whole bunch of data, and the app then crashed because you types "," instead of "." you'd be pretty annoyed - so allow users to make mistakes and get them to correct them!

Hmmmmm. I been thinking, since the Textbox name is txtPrice, I was wondering if the box is holding string with currency format like (£12.30). If that the case, try follow the below example

System.Globalization.CultureInfo provider = new System.Globalization.CultureInfo("en-GB");
    string txtPrice = "£12.30";
    double price;
    double.TryParse(txtPrice, System.Globalization.NumberStyles.AllowThousands |
      System.Globalization.NumberStyles.AllowDecimalPoint |
      System.Globalization.NumberStyles.AllowCurrencySymbol, provider, out price);
    product.Price = price;

Output: 12.3
if price is an integer

product.Price = (int)price;

Output: 12

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