Pointers in C

Pointers are variables that store memory addresses. They provide a powerful way to manipulate memory and improve performance.

Declaring and Initializing Pointers

1. Declaration

A pointer is declared using the * operator.

int *ptr; // Declaring a pointer to an integer

2. Initialization

Pointers store the address of another variable.

int num = 10;
int *ptr = # // Pointer stores the address of num

Accessing Values using Pointers

The * operator (dereference) is used to access the value at the memory location.

printf("Value of num: %d", *ptr); // Outputs 10

Pointer Arithmetic

Pointers support arithmetic operations such as increment, decrement, addition, and subtraction.

ptr++; // Moves to the next memory location

Pointers and Arrays

An array name acts as a pointer to the first element of the array.

int arr[] = {1, 2, 3};
int *ptr = arr; // Points to the first element
printf("%d", *(ptr + 1)); // Outputs 2

Pointers and Functions

Pointers can be used to pass variables by reference to functions.

void changeValue(int *p) {
    *p = 20; // Modifies the original value
}

int main() {
    int num = 10;
    changeValue(&num);
    printf("%d", num); // Outputs 20
}

Pointer to Pointer

A pointer can store the address of another pointer.

int num = 10;
int *ptr = #
int **pptr = &ptr; // Pointer to pointer
printf("%d", **pptr); // Outputs 10

Dynamic Memory Allocation

Pointers are used for dynamic memory allocation with functions like malloc(), calloc(), and free().

Example: Allocating Memory Dynamically

#include <stdio.h>
#include <stdlib.h>

int main() {
    int *ptr = (int*) malloc(sizeof(int));
    *ptr = 50;
    printf("Value: %d", *ptr);
    free(ptr); // Free allocated memory
}

Pointers are essential in C programming for memory management, data structures, and efficient programming techniques.

If you have any questions, feel free to ask. Thank you for reading!