为什么DateTime的GetType不是常量值 [英] Why the GetType of DateTime is not a constant value

问题描述

Hi Folks，

我正在处理带有类型检查的switch语句..以下代码适用于所有类型，但是，挑战是使用Nullable类型。

I'm working on a switch statement with Type checking .. The following code is working perfectly well for all the types, but, the challenge is with Nullable types.

                        switch (Type.GetTypeCode( propertyInfos.PropertyType))
                        {
                            // Type code doesn't have reference with int, long, etc.,
                            case TypeCode.DateTime:
                                // Do the work for DateTime
                                break;
                            case TypeCode.Int32 :
                                // Do the work for Int32
                                break;
                            case TypeCode.Int64:
                                // Do the work for long
                                break;
                            case TypeCode.DateTime? :
                                break;
                            default:
                                break;
                        }

我试过将其更改为GetType和DateTime.Today.GetType（）。ToString（）会将System.DateTime作为字符串给出。但是，使用时，编译器会抛出错误，因为它不是有效的常量字符串。在任何给定的时间实例，DateTime.Today.GetType（）
总是会给我们"System.DateTime"，为什么编译器不接受这个？

I have tried that to change as GetType and DateTime.Today.GetType().ToString() would give us System.DateTime as a string. But, when used the compiler throws error as that is not a valid Constant string. At any given time instance, DateTime.Today.GetType() would always gives us "System.DateTime", why this is not accepted by compiler?

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推荐答案

...  ，但挑战是Nullable类型。

可以为空的'DateTime？'不是
TypeCode 枚举。因此，您的代码将导致语法错误。最好在对象进入switch语句之前检查null并抛出NullReferenceException。

The nullable 'DateTime?' is not a valid member of the TypeCode enumeration. So, your code will cause a syntax error. Better to check for null before your object enters the switch statement and throws a NullReferenceException.

wizend

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