Pointers in C

Introduction

A pointer in C is a variable that stores the memory address of another variable. Pointers are powerful tools for dynamic memory management, arrays, and function calls. Understanding pointers is essential for advanced C programming.

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Key Points

1. Pointer Declaration

• Syntax: dataType *pointerName;
• Example: int *ptr;

2. Pointer Initialization

• Assign the address of a variable using &: int a = 10; int *ptr = &a;

3. Dereferencing a Pointer

• Access the value stored at the memory address using *: printf("%d", *ptr); // Outputs 10

4. Null Pointer

• Pointer that does not point to any valid memory: int *ptr = NULL;

5. Pointer Arithmetic

• Add/subtract integers to move to other memory locations: ptr++; // Moves to next memory location of int

6. Pointers and Arrays

• Array name acts as a pointer to the first element: int arr[3] = {10, 20, 30}; int *p = arr; // Points to arr[0] printf("%d", *(p + 1)); // Outputs 20

7. Advantages

• Efficient memory usage
• Dynamic memory allocation
• Allows passing large data to functions without copying

8. Limitations

• Incorrect use can cause memory leaks
• Can lead to segmentation faults
• Requires careful handling

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Example Code

#include <stdio.h>
int main() {
    int a = 10;
    int *ptr = &a;
    printf("Address of a: %p\n", ptr);
    printf("Value of a using pointer: %d\n", *ptr);
    return 0;
}