Pointers are variables that hold address of another variable of same data type. Pointers are one of the most distinct and exciting features of C language. It provides power and flexibility to the language. Although pointer may appear little confusing and complicated in the beginning, but trust me it’s a powerful tool and handy to use once it’s mastered.
Benefit of Using Pointers:
- Pointers are more efficient in handling Array and Structure.
- Pointer saves the memory space.
- It reduces length and the program execution time.
- Pointers are used to allocate memory dynamically.
Concept of Pointer:
Whenever a variable is declared, system will allocate a location to that variable in the memory, to hold value. This location will have its own address number.
Let us assume that, system has allocated memory location 80F for a variable a.
int a = 10 ;
We can access the value 10 by either using the variable name a or the address 80F. Since the memory addresses are simply numbers they can be assigned to some other variable. The variable that holds memory address are called pointer variables. A pointer variable is therefore nothing but a variable that contains an address, which is a location of another variable. Value of pointer variable will be stored in another memory location.
Declaring a Pointer Variable:
Syntax of pointer declaration is:
data-type *pointer_name;
Data type of pointer must be same as the variable, which the pointer is pointing.
Initialization of Pointer variable:
Pointer Initialization is the process of assigning address of a variable to pointer variable. Pointer variable contains address of variable of same data type. In C language address operator & is used to determine the address of a variable. The & returns the address of the variable associated with it.
int a = 10 ; int *ptr ; //pointer declaration ptr = &a ; //pointer initialization
or we can mention
int *ptr = &a ; //initialization and declaration together
Pointer variable always points to same type of data.
float a; int *ptr; ptr = &a; //ERROR due to type mismatch.
Dereferencing of Pointer:
Once a pointer has been assigned the address of a variable. To access the value of variable, pointer is dereferenced, using the indirection operator *.
int a,*p;
a = 10;
p = &a;
printf("%d",*p); //this will print the value of a.
printf("%d",*(&a)); //this will also print the value of a.
printf("%u",&a); //this will print the address of a.
printf("%u",p); //this will also print the address of a.
printf("%u",&p); //this will also print the address of p.
Author
Mr.Rahul Agarwal
Associate Professor, Department of CS & IT
Biyani Group of Colleges,Jaipur
