Dynamic Memory – malloc & free

The heap provides memory at runtime via <stdlib.h> functions:

• void *malloc(size_t size) – allocate uninitialized memory.
• void *calloc(size_t count, size_t size) – allocate zero‑initialized memory.
• void *realloc(void *ptr, size_t newSize) – resize an existing block.
• void free(void *ptr) – return memory to the system.

Always check the pointer returned by malloc/calloc for NULL. Forgetting free causes memory leaks; double‑free leads to undefined behavior.