Question

Define union. Compare Structure and Union. 

Answer 1

Union :- A union is a special data type available in C that allows storing different data types in the same memory location.  

	Structure	Union
Keyword	The keyword ‘struct’ is used to define a structure.	The keyword ‘union’ is used to define a union.
Size	When a variable associated with a structure, the compiler allocates the memory for each member. The size of structure is greater than or equal to the sum of sizes of its members.	When a variable associated with a union, the compiler allocates the memory by considering the size of the largest memory. Hence, The size of union is equal to the size of largest members.
Memory	Each member within a structure is assigned and unique storage area of location.	Memory allocated is shared by individual members of union.
Value Altering	Altering the value of a member will not affect other members of the structure	Altering the value of any of the member will alter other member values.
Accessing members	Individual member can be accessed at a time.	Only one member can be accessed at a time.
Initializing Members	Several members of a structure can initialize at once.	Only the first member of a union can be initialized.