请帮我修复此错误。 [英] Please help me to fix this error.

问题描述

decimal DisCp = Convert.ToDecimal（txtDiscountedCashPrice.Text.Trim（））* Convert.ToInt16（txtQuantity.Text.Trim（））;



我尝试过：



decimal DisCp = Convert.ToDecimal（txtDiscountedCashPrice.Text.Trim（））* Convert.ToInt16（txtQuantity.Text。 Trim（））;

decimal DisCp = Convert.ToDecimal(txtDiscountedCashPrice.Text.Trim()) * Convert.ToInt16(txtQuantity.Text.Trim());

What I have tried:

decimal DisCp = Convert.ToDecimal(txtDiscountedCashPrice.Text.Trim()) * Convert.ToInt16(txtQuantity.Text.Trim());

推荐答案

简单：不要在用户输入上使用转换。

相反，使用适当的TryParse方法：

Simple: don't use Convert on user input.
Instead, use the appropriate TryParse methods:

decimal discountedCashPrice, quantity;
if (!decimal.TryParse(txtDiscountedCashPrice.Text.Trim(), out discountedCashPrice))
   {
   ... report problem to user
   return;
   }
if (!decimal.TryParse(txtQuantity.Text.Trim(), out quantity))
   {
   ... report problem to user
   return;
   }
decimal DisCp = discountedCashPrice * quantity;

如果用户输入错误，转换方法总是抛出异常 - 他们这样做，用户，所有的时间 - 但TryParse方法没有 - 他们允许你优雅地告诉用户问题是什么，并让他修复它而不是崩溃你的应用程序。

The Convert methods always throw an exception if the user enters something wrong - and they do that, users, all the time - but the TryParse methods don't - they allow you to gracefully tell the user what the problem is, and let him fix it instead of crashing your app.

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