What are the different storage classes in C ?

C has three types of storage: automatic, static and allocated. 

Variable having block scope and without static specifier have automatic storage duration. 

Variables with block scope, and with static specifier have static scope. Global variables (i.e, file scope) with or without the the static specifier also have static scope. 

Memory obtained from calls to malloc(), alloc() or realloc() belongs to allocated storage class.