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Programming for Problem Solving Unit-5 One Shot + PYQ Solutions Topic 1: Pointers A pointer is a special variable that stores the address of another variable. 👉 Think of a pointer like a house address written on paper. The address (pointer) tells you where the house (data) is located, not what's inside it. Why Use Pointers? They allow direct memory access, efficient data manipulation, and are essential for dynamic memory allocation and data structures like linked lists. 🔸 What is a Pointer? 🔸 Declaration and Initialization int *ptr; → means ptr is a pointer to an integer. &a → means "address of a" So ptr = &a; → ptr now holds the address of a.

💡 If ptr was at address 1000, after ptr++, it becomes 1004 (because an int is usually 4 bytes). Output: Compilation error or undefined behavior. Explanation: A void* pointer can hold any address but cannot be dereferenced directly (using *ptr) because the compiler doesn’t know the data type. Topic 2: Dynamic Memory Allocation Unlike static memory (fixed at compile time, e.g., int arr[10];), dynamic memory is allocated at runtime using functions like malloc, calloc, realloc, and free. What is Dynamic Memory Allocation?
✅ Why Do We Need Dynamic Memory Allocation? In regular arrays like int arr[50];, size is fixed at compile time. ❌ If size is too small, we can't store all data. ❌ If size is too large, we waste memory. 💡 Dynamic Allocation allows us to: Create memory during runtime Resize it as per requirement Use heap memory (instead of stack) All these functions are in the stdlib.h header. 🔧 Functions Used for DMA in C 📘 Check before using: Allocates memory for 5 integers. Memory contains garbage values (not initialized). Returns NULL if memory fails to allocate. malloc() – Memory Allocation Subscribe Multi Atoms & Multi Atoms Plus Join Telegram Channel Follow us on Instagram