Which of the following is not user defined data type? 1 : struct book { char name[10]; float price; int pages; }; 2 : long int l = 2.35; 3 : enum day {Sun, Mon, Tue, Wed};

1. Primary data types
   1. int
   
   
   2. char
   
   
   3. float
   
   
   4. double
   
   
   5. void


2. Secondary data types (or) User-defined data type
   1. Array
   
   
   2. Pointer
   
   
   3. Structure
   
   
   4. Union
   
   
   5. Enum

So, clearly long int l = 2.35; is not User-defined data type.
(i.e.long int l = 2.35; is the answer.)