问题
Hey I just came across the following statement
return name != null ? name : "NA";
I am just wondering what this is called in .NET
does the ? stand for i.e. then do this... ?
回答1:
It's a "conditional operator" commonly known as the Ternary operator
It's found in many programming languages.
回答2:
Just to add to everyone else's answers, note that in...
condition ? trueResult : falseResult
...only condition and either trueResult or falseResult (but not both) will be evaluated. That makes it possible to write code like this...
string name = user == null ? "<nobody>" : user.Name;
...without the risk of a NullReferenceException being thrown since user.Name will only be evaluated if user is non-null. Compare this behavior with VB.NET's If operator and IIf function.
回答3:
As Lion said in the comments, they are called ternary operators, though they are also known as inline if statmenets and conditional operator.
If you want to find out more about them, this Wikipedia page will help, and it has examples for many programming languages: http://en.wikipedia.org/wiki/%3F:
回答4:
This is the conditional operator which is a ternary operator. Since there are not so many other ternary operators (operator with three arguments) many people believe its called ternary operator, which is imprecise!
来源：https://stackoverflow.com/questions/9695493/c-sharp-using-if-else-statements-to-set-value-whats-this-called