C++ Memory Model

1// Stack memory (automatic storage)
2void stackExample() {
3    int x = 10;       // Stack
4    int arr[100];     // Stack
5}  // Automatically freed
6
7// Heap memory (dynamic storage)
8void heapExample() {
9    int* p = new int(10);  // Heap
10    delete p;              // Must free manually
11}
12
13// Memory segments:
14// - Text: compiled code
15// - Data: global/static initialized variables
16// - BSS: global/static uninitialized (zero)
17// - Heap: dynamic allocation (grows up)
18// - Stack: local variables (grows down)
19
20// Static storage duration
21static int counter = 0;  // Lives entire program
22
23// Thread-local storage (C++11)
24thread_local int threadCounter = 0;
25
26// Object layout
27struct Example {
28    char a;    // 1 byte + 3 padding
29    int b;     // 4 bytes
30    char c;    // 1 byte + 3 padding
31};  // Total: 12 bytes (with padding)
32
33// Alignment
34alignas(16) int aligned;  // 16-byte aligned