Pointers in C programming

Introduction

What is C Pointers

Pointer declaration in C programming

Syntax

int *a;//pointer to int 
char *c;//pointer to char 

Example

#include<stdio.h> 
int main(){ 
int number=120; 
int *p; 
p=&number;//stores the address of number variable 
printf("Address of p variable is %x \n",p); // p contains the address of the number therefore printing p gives the address of number. 
printf("Value of p variable is %d \n",*p); // As we know that * is used to dereference a pointer therefore if we print *p, we will get the value stored at the address contained by p. 
return 0; 
} 

Output

Address of number variable is fff4
Address of p variable is fff4
Value of p variable is 120

Array pointers in c

Function pointer in c

Pointer to Structure in C

Advantages of using Pointers in C

• Dynamic memory allocation: Pointers allow to dynamically allocate memory during runtime. This means that can allocate memory for data structures like arrays, linked lists, and trees, which can be resized or deallocated as needed. This gives greater control over memory usage and can help optimize the program's performance.
• Passing by reference: Pointers allow passing data by reference to functions. This means that can modify the original data within the function, rather than creating a copy of it. This can be more efficient than passing by value, especially for large data structures.
• Manipulating data structures: Pointers allow to manipulate data structures directly. For example, one can traverse a linked list or a tree by following the pointers between nodes. This can be more efficient than copying or moving data between structures.
• Interfacing with system functions: Many system functions in C require the use of pointers. For example, the malloc() function returns a pointer to a block of memory, which can be used to store data. Pointers are also used extensively in system calls and low-level I/O operations.
• Flexibility: Pointers are a flexible and powerful tool that can be used in a variety of ways. They allow to creation complex data structures, implement algorithms, and manipulate memory directly. While they can be more difficult to use than other data types, the benefits they provide make them an essential tool for many programming tasks.

Usage of Pointers in C

• Dynamic Memory Allocation: Pointers are used to allocate memory dynamically at run time using functions like malloc() and calloc(). This allows to create data structures such as arrays and linked lists of arbitrary size.
• Structures: Usage of Pointers in C to manipulate structures, which are collections of variables of different types.
• Passing Arguments to Functions: Pointers can be used to pass arguments to functions by reference, allowing the function to modify the values of variables passed to it.
• Arrays: In C, an array name is a pointer to the first element of the array. The developer can use pointer arithmetic to access elements of an array.
• Pointers to Functions: The developer can define pointers to functions in C, which can be used to pass functions as arguments to other functions, or to create callback functions.
• Strings: In C, strings are arrays of characters. Pointers are commonly used to manipulate strings by accessing individual characters in the string.

Null pointer in C

C language is one of the most widely used programming languages. However, coding in C requires a lot of attention to avoid errors that can lead to program failure. One of the errors that are common in C is the Null Pointer error. A Null Pointer error, also known as a segmentation fault, occurs when a program tries to access memory that does not exist. This occurs when a pointer is assigned a null value, i.e., a value of zero. C programmers need to understand this error and how to avoid it. Handling Null Pointer in C is critical to developing high-quality code.

Summary

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