问题
What is the usage of these operators?
回答1:
Basically when you want to provide conversions between types. LINQ to XML provides good examples... There's an implicit conversion from string to XName, so you can write:
XName name = "element";
but there's an explicit conversion from XAttribute to int (and many other types) so you have to include a cast in your code:
int value = (int) element.Attribute("age");
Think very carefully before providing implicit conversions - they're rarely a good idea; LINQ to XML uses them to great effect, but they can be confusing. Even explicit user-defined conversions can surprise the unwary reader.
回答2:
They are used when doing operator overloading. Here's a link to a MSDN article.
来源：https://stackoverflow.com/questions/2371011/when-must-we-use-implicit-and-explicit-operators-in-c