“时间跨度”是什么意思？ c# 的意思是什么？

Question

what does the question mark mean at the end of the variable?

TimeSpan? begin = // bla bla bla

The coding language is c#

Answer 1

This is Nullable type. It means that value of begin can be null or a timespan

TimeSpan? and Nullable<Timespan> is same thing

Answer 2

TimeSpan? means you're declaring a nullable type. A type which can support null values.