# memory

***

**1. Dynamic Memory Allocation**

```cpp
int* ptr = new int;  // Allocate memory for an integer
*ptr = 10;  // Store value in allocated memory
delete ptr;  // Release allocated memory
```

**2. Static Memory Allocation**

```cpp
int arr[10];  // Declare and initialize array of 10 integers
arr[0] = 10;  // Store value in array
```

**3. Shared Memory**

```cpp
int* shm = (int*)mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
*shm = 10;  // Share memory and store value
munmap(shm, sizeof(int));  // Unmap shared memory
```

**4. Virtual Memory**

```cpp
void* addr = mmap(NULL, 1024, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
memcpy(addr, "Hello", 5);  // Write data to virtual memory
munmap(addr, 1024);  // Unmap virtual memory
```

**5. Memory Mapping**

```cpp
int* ptr = (int*)mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
*ptr = 10;  // Map file into memory and store value
munmap(ptr, sizeof(int));  // Unmap file
```

**6. Memory Pool**

```cpp
std::pmr::memory_resource mem_pool;
int* ptr = (int*)mem_pool.allocate(sizeof(int));
*ptr = 10;
mem_pool.deallocate(ptr, sizeof(int));
```

**7. Thread-Local Storage**

```cpp
struct ThreadData {
  int value;
};
__thread ThreadData thread_data;
thread_data.value = 10;  // Store value in thread-local memory
```

**8. Memory Ordering**

```cpp
std::atomic<int> value = 0;
value.store(10, std::memory_order_seq_cst);  // Store value in atomic memory with strong ordering
int result = value.load(std::memory_order_seq_cst);  // Load value with strong ordering
```

**9. Memory Barrier**

```cpp
std::atomic_thread_fence(std::memory_order_seq_cst);  // Insert memory barrier to ensure ordering
```

**10. Memory Alignment**

```cpp
int* ptr = (int*)aligned_alloc(16, sizeof(int));  // Allocate aligned memory
*ptr = 10;
free(ptr);
```

**11. Memory Debugger**

```cpp
#ifdef _DEBUG
malloc_dbg(ptr, _CRT_DBGF_ALLOCATED);  // Track allocations in a debug build
#endif
```

**12. Memory Leak Detection**

```cpp
#ifdef _WIN32
_CrtDumpMemoryLeaks();  // Detect memory leaks in Windows
#endif
```

**13. Memory Profiler**

```cpp
#ifdef __has_feature(memory_sanitizer)
__msan_init();  // Enable memory sanitizer for profiling
#endif
```

**14. Memory Optimization**

```cpp
#ifdef __has_feature(memory_sanitizer)
__msan_set_track_origins(1);  // Track allocation origins for optimization
#endif
```

**15. Memory Protection**

```cpp
int* ptr = (int*)mmap(NULL, sizeof(int), PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
*ptr = 10;  // Map memory with read-only protection
```

**16. Memory Initialization**

```cpp
int arr[10] = {};  // Initialize array with zeros
```

**17. Memory Comparison**

```cpp
int* ptr1 = new int;
int* ptr2 = new int;
bool equal = (ptr1 == ptr2);  // Compare memory addresses
```

**18. Memory Copying**

```cpp
memcpy(dest, src, sizeof(int));  // Copy memory from one location to another
```

**19. Memory Movement**

```cpp
memmove(dest, src, sizeof(int));  // Move memory, handling overlapping data
```

**20. Memory Set**

```cpp
memset(dest, 0, sizeof(int));  // Set memory to a specific value
```

**21. Memory Fill**

```cpp
std::fill(arr, arr + 10, 10);  // Fill an array with a value
```

**22. Memory Swap**

```cpp
std::swap(ptr1, ptr2);  // Swap memory pointers
```

**23. Memory Reverse**

```cpp
std::reverse(arr, arr + 10);  // Reverse the order of elements in an array
```

**24. Memory Sort**

```cpp
std::sort(arr, arr + 10);  // Sort the elements in an array
```

**25. Memory Search**

```cpp
int* ptr = std::find(arr, arr + 10, 10);  // Search for a value in an array
```

**26. Memory Filtering**

```cpp
std::vector<int> vec = std::vector<int>(arr, arr + 10);
vec.erase(std::remove(vec.begin(), vec.end(), 10), vec.end());  // Filter a vector by removing specific elements
```

**27. Memory Transformation**

```cpp
std::transform(arr, arr + 10, arr, [](int& n) { return n * 2; });  // Transform the elements in an array
```

**28. Memory Reduction**

```cpp
std::vector<int> vec = std::vector<int>(arr, arr + 10);
vec.shrink_to_fit();  // Reduce the capacity of a vector to its size
```

**29. Memory Allocation Guard**

```cpp
std::malloc_guard guard;  // Enable malloc guard to detect buffer overflow
```

**30. Memory Deinitialization**

```cpp
delete[] arr;  // Deallocate dynamically allocated array
```

**31. Memory State Checking**

```cpp
assert(ptr != NULL);  // Assert that a pointer is not null
```

**32. Memory Profiling Tools**

```cpp
#define _CRTDBG_MAP_ALLOC
int main() {
  _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF);  // Enable memory profiling and leak detection
  {
    // Allocate and use memory
  }
  _CrtDumpMemoryLeaks();  // Dump memory leak report
}
```

**33. Memory Cache Optimization**

```cpp
std::unordered_map<int, int> cache;  // Use a cache to optimize memory access for frequently used data
```

**34. Memory Reference Counting**

```cpp
std::shared_ptr<int> ptr = std::make_shared<int>(10);  // Create a shared pointer with reference counting
```

**35. Memory Weak Pointers**

```cpp
std::weak_ptr<int> ptr = std::weak_ptr<int>(shared_ptr);  // Create a weak pointer that doesn't increment reference count
```

**36. Memory Management Unit (MMU)**

```cpp
// Enable memory protection in MMU
__set_memory_protection(addr, PROT_READ | PROT_WRITE);
```

**37. Memory Translation Lookaside Buffer (TLB)**

```cpp
// Query TLB to optimize memory access
unsigned long long addr = 0x12345678;
int* page = (int*)__builtin_ia32_lookup_tlb(addr);
```

**38. Memory Pre-Fetching**

```cpp
// Pre-fetch memory to improve performance
__builtin_prefetch(addr, 0);
```

**39. Memory Paging**

```cpp
// Manage memory pages
struct mmap {
  void* addr;  // Page address
  size_t size;  // Page size
};
mmap* pages = (mmap*)mmap_pages(0, 1024 * 1024, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS);
```

**40. Memory Unmap**

```cpp
// Unmap memory pages
munmap(pages, 1024 * 1024);
```

**41. Memory Segmentation**

```cpp
// Create memory segments
struct segment {
  void* start;  // Segment start address
  size_t size;  // Segment size
};
segment seg = (segment)mmap_segment(0, 1024 * 1024, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS);
```

**42. Memory Protection**

```cpp
// Protect memory pages
mprotect(pages, 1024 * 1024, PROT_READ);
```

**43. Memory Synchronization**

```cpp
// Synchronize memory access
std::atomic<int> counter = 0;
```

**44. Memory Barriers**

```cpp
// Insert memory barriers to ensure synchronization
std::memory_barrier();
```

**45. Memory Transactions**

```cpp
// Use memory transactions for atomic operations
struct atomic_int {
  std::atomic<int> value;
  bool CompareExchange(int expected, int new_value) {
    return value.compare_exchange_weak(expected, new_value);
  }
};
```

**46. Memory Allocation Optimization**

```cpp
// Optimize memory allocation with memory pools
struct memory_pool {
  void* base;  // Pool base address
  size_t size;  // Pool size
  size_t free_size;  // Free space in pool
  void* Allocate(size_t size) {
    if (size <= free_size) {
      void* ptr = base + offset;
      offset += size;
      free_size -= size;
      return ptr;
    }
    return NULL;
  }
};
```

**47. Memory Leak Detection**

```cpp
// Use memory debugging tools to detect memory leaks
#ifdef _DEBUG
  _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF);
  _CrtDumpMemoryLeaks();
#endif
```

**48. Memory Profiling**

```cpp
// Use memory profiling tools to optimize memory usage
#ifdef _DEBUG
  _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_MAP_ALLOC);
  _CrtDumpMemoryLeaks();
#endif
```

**49. Memory Compression**

```cpp
// Compress memory to reduce memory usage
#ifdef LZ4
  char* compressed_data = LZ4_compress(data, sizeof(data));
  // Use compressed data
  LZ4_decompress(compressed_data, data, sizeof(data));
#endif
```

**50. Memory Encryption**

```cpp
#ifdef OPENSSL
  EVP_CIPHER_CTX ctx;
  EVP_CipherInit_ex(&ctx, EVP_aes_256_cbc(), NULL, key, iv, 1);
  EVP_CipherUpdate(&ctx, ciphertext, &ciphertext_len, data, sizeof(data));
  EVP_CipherFinal_ex(&ctx, ciphertext + ciphertext_len, &final);
#endif
```