Q: What are User Defined data types?

C supports an extraordinary feature known as "type definition" that permits users to define an identifier that would represent an existing data type. The typedef statement redefines the name of an available variable type. Consider the instance where the type unsigned long int is redefined to be of type ULINT.

typedef unsigned long int ULINT;

Now we can state variables of the type unsigned long int by writing

ULINT xl,x2;

Instead of writing the long declaration.

That signifies typedef provides a short and meaningful way to call a data type. By reducing apparent complexity and the length of data types typedef can help to clarify source listing and to save energy and time spend in understanding a program.

The universal syntax of a typedef command can be written as

typedef data - type identifier