Final answer:
An array is a data structure that stores a fixed-size sequence of elements. A pointer is a variable that stores the memory address of another variable. A struct is a user-defined data type that groups together related data items of different types.
Step-by-step explanation:
(a) Array: An array is a data structure that stores a fixed-size sequence of elements of the same type. The elements in an array are linked by their indices, which are integers starting from 0. Array elements can be accessed by their indices, for example, arr[0] or arr[1].
(b) Pointer: A pointer is a variable that stores the memory address of another variable. Pointers allow direct memory manipulation and can be used to dynamically allocate memory. Pointers can be dereferenced to access or modify the value of the variable they point to.
(c) Struct: A struct is a user-defined data type in C that groups together related data items of different types into a single unit. It can be used to create complex data structures that can hold multiple values. The members of a struct can be accessed using the dot operator.
(d) Int: 'Int' is the keyword used to declare a variable of type integer in C. Integers are whole numbers without any fractional or decimal part. They can be positive, negative, or zero.