QnA.md

DTO

• Data Transfer Object, the main purpose of the pattern is to reduce the number of methods calls(reduce roundtrips to the server by batching up multiple parameters in a single call => reduce network overhead)
• Additionally, we can hide informations instead of exposing all the fields

C# null conditional operator(?.)

• it can be interpreted as null-conditional member operator
• if left-hand operand is null, return null
• else, return the right-hand member

C# bit-wise shift operators

• >>>: logical shift
• >>: arithmetic shift
• <<: discards high-order bits, fill left with zeros

C# null co-alescing operator(??)

• return left-hand operand when left-hand operand is not null
• return right-hand operand when left-hand operand is null

C# pattern matching in switch-case statement

• pack the data into object datatype
• then, we can use datatype to specify each cases
• (additional) we can also use case guard within thet each cases
• so, we can write like this: case float f when f >= 0:
• this corresponds to the statement that given argument is float and bigger than 0

C# switch expression

• we can use switch expression in C#
• i.e.

  string grade = score switch
  {
      90 when repeated == true => "B+",
      90 => "A",
      80 => "B",
      70 => "C",
      60 => "D",
      _ => "F"        // <- discard pattern in C#
  }