Pointers in C — Complete Guide

Pointers are one of the most powerful and fundamental features in the C programming language. If you truly understand pointers, you unlock low-level memory control, efficient data structures, and system-level programming. 1. What is a Pointer? A pointer is a variable that stores the memory address of another variable. int a = 10; int *p = &a; Memory Diagram Stack Memory: +------------+ +------------+ | a = 10 | 0x100 | p = 0x100 | 0x200 +------------+ +------------+ p ───────────────► a Debug Scenario ❌ Bug: printing pointer incorrectly printf("%d", p); // WRONG ✅ Fix: printf("%p", (void*)p); 2. Pointer Declaration data_type *pointer_name; Memory Insight The pointer size is fixed (typically 4 or 8 bytes), regardless of type. int *p; // 8 bytes (on 64-bit system) char *c; // 8 bytes Debug Scenario ❌ Misinterpretation bug char *p; int x = 1000; p = (char*)&x; printf("%d", *p); // unexpected value 3. Address Operator (&) int x = 5; printf("%p", &x); Memory Diagram +-------