Introduction To Pointers | Pointers

What is a Pointer?

A pointer in C is a variable that stores the memory address of another variable. Instead of holding a data value, a pointer holds the address of a variable where data is stored. This allows for efficient array manipulation, memory management, and dynamic memory allocation.

Declaration of Pointers

Pointers are declared using the * operator. The syntax for declaring a pointer is:

data_type *pointer_name;

For example, to declare a pointer to an integer:

int *ptr;

Initializing Pointers

Pointers are initialized by assigning the address of another variable to the pointer. The address-of operator & is used to obtain the address of a variable.


                    int var = 10;

                    int *ptr = &var;  /* ptr now holds the address of var */

Dereferencing Pointers

Dereferencing a pointer involves accessing the value stored at the memory address held by the pointer. The * operator is used for dereferencing.


                    int var = 10;

                    int *ptr = &var;

                    int value = *ptr;  /* value now holds the value of var */

Pointer Arithmetic

Pointers can be incremented or decremented to point to the next or previous memory location. The amount by which a pointer is incremented or decremented depends on the data type it points to.


                    int arr[3] = {10, 20, 30};

                    int *ptr = arr;

                    ptr++; /* Now ptr points to arr[1] */

Example Program

Let's look at a complete example of using pointers in a C program:


                    #include <stdio.h>


                    int main() {

                        int var = 10;

                        int *ptr = &var;

                    

                        printf("Address of var: %p\n", (void*)&var);

                        printf("Address stored in ptr: %p\n", (void*)ptr);

                        printf("Value of var: %d\n", var);

                        printf("Value pointed to by ptr: %d\n", *ptr);

                    

                        return 0;

                    }

The output of the above program would be:

Address of var: 0x7ffee3b12a9c
Address stored in ptr: 0x7ffee3b12a9c
Value of var: 10
Value pointed to by ptr: 10

Conclusion

Pointers are a fundamental concept in the C language that provide a powerful way to manage memory and interact with data. By understanding how to declare, initialize, and use pointers, you can write more efficient and flexible C programs.

Introduction to Pointers in C