datetime变量出错 [英] Error in datetime variable

问题描述

string carName =;

DateTime dateFrom =;



有错误吗？

string carName = "";
DateTime dateFrom = "";

Is there any error?

推荐答案

是的。下一个！





哦，你想了解更多细节吗？好的......

如果你试图编译它，你会收到一个错误：

Yes. Next!


Oh, you want more details? OK...
if you try to compile that, you will get an error:

Cannot implicitly convert type 'string' to 'System.DateTime'

因为你不能只为一个DateTime分配一个字符串，而不是在一个圆孔中推一个方形钉。

DateTime不是字符串数据类型：它是一个值，表示自任意时间点以来的毫秒数。即使你想给它分配一个空白值，你也不能，因为就像整数它没有空白数字的概念 - 它有一个零，就像整数做（DateTime.MinValue）但它没有空白值，所以即使你尝试了正确的方式，通过使用DateTime.Parse或DateTime将字符串值赋值给DateTime .ParseExact如果你试图解析一个空字符串会引发异常！



想想你想要实现的目标，并且可能有更好的方法尝试到达那里 - 但这不会起作用！

Because you can't just assign a string to a DateTime any more than you can push a square peg in a round hole.
DateTime is not a string data type: it's a value which represents the number of milliseconds since and arbitrary point of time. Even if you wanted to assign a "blank" value to it, you can't, because just like integer it doesn't have a concept of "blank number" - it has a zero, just like integers do (DateTime.MinValue) but it doesn't have a "blank" value, so even if your tried the "proper" way to assign a string value to a DateTime by using DateTime.Parse or DateTime.ParseExact it would throw an exception if you tried to parse a blank string!

Think about what you are trying to achieve and there may be a better way to try and get there - but that isn't going to work!

我希望你非常敏锐地观察下面的内容：

I want you to observe the below stuff very keenly:

Quote：

string carName =;

DateTime dateFrom =;

string carName = "";
DateTime dateFrom = "";

以下代码特别之处???为什么编译???

Whats special in the below code??? Why does it compile???

Quote：

string carName = ;

DateTime dateFrom = DateTime.Parse（）;

string carName = "";
DateTime dateFrom = DateTime.Parse("");

如果我这样做？

What if i do?

Quote：

DateTime dateFrom = Convert.ToDateTime（）;

DateTime dateFrom = Convert.ToDateTime("");

最后一期：



什么如果你问我50

Last question:

What if you ask me 50

我给你50Rs有什么区别？





谢谢

and i give you 50Rs what is the difference?


Thanks

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