Basic Computation and Programming with C

Any physical entity can be accessed by its name as well as its address. For example, if address of the building, ‘Chatterjee International Centre’ is ‘33A, Chowringhee Road, Kol-71’, then to mention the building we can say ‘Chatterjee International Centre’ or the building at ‘33A, Chowringhee Road, Kol-71’. The same concept is applicable for accessing variables also. This means even though we accessed the variables by its name so far but we can access them by their address also. In this chapter, we will discuss about the accessibility of the variables by means of their addresses.

(Note that ‘a building having address but not having any name’ is possible but ‘a building having a name but not having any address’ cannot exist. Similarly all variables should have a unique memory address, but a memory address not having a unique variable name can still be accessed by its address using the pointer pointing to it.)

POINTER

Pointer provides a flexible, powerful and efficient method to manipulate data in our programs. In C language, a pointer is a variable that can store the address of some memory location. Each memory location in the computer, i.e., in the RAM has an address. By storing that address a pointer variable actually points to or references the particular memory location where the data are stored. As now a pointer variable can be used to access memory locations, the content of the memory locations can be accessed and modified easily.