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Memory Management Basics

Stack vs heap, allocation, garbage collection, leaks.

memorybasicsUpdated 2025-09-01

Stack vs Heap

  • Stack: automatic, function frames, fast.
  • Heap: dynamic allocation (new / malloc), manual or GC.

Lifecycle

  • Allocate → Use → Release (manual) or GC sweeps unreachable objects.

Problems

  • Leaks: lost reference to allocated block.
  • Dangling pointer: freed memory still referenced.
  • Fragmentation: many small gaps.

Example (Java)

  • int x = 10; // stack primitive
  • int[] a = new int[3]; // heap array