C data types are categorized into primitive (basic), derived, and user-defined types.
1. Primitive Data Types:
These are the fundamental types provided by the language that are not composed of other types. They include int, char, float, and double. Modifications like long, short, signed, and unsigned are considered part of these basic types. Therefore, long int is a primitive type.
2. User-Defined and Derived Types:
• struct: A user-defined type that groups different types.
• union: Similar to struct, but all members share the same memory location.
• enum: A user-defined type used to assign names to integral constants.
3. Distinction:
While struct, union, and enum allow users to define their own data structures, long int is built directly into the C compiler's keyword system to represent large integers.