Which of following is a user-defined type?

Question

Which of following is a user-defined type? And why?
A) double
B) unsigned long int
C) enum
D) long int

Answer 1

Cases a,b,d are predefined language types. Enum is a key for user-defined new types. Example:

enum Color {Blue, Red, Green};

enum Color myColor = Blue;

Answer 2

Enums are user-defined. You can read more about enums here: https://www.geeksforgeeks.org/enumeration-enum-c/. Hope it helps you.