1. Overview Memory management is a core responsibility in C and C++. Unlike garbage-collected languages, the programmer directly controls memory allocation, use, and deallocation. This offers performance and flexibility but risks leaks, corruption, and undefined behavior. 2. Key Memory Regions (Segments) | Segment | Contents | Lifetime | |-------------|-----------------------------------------|-----------------------------| | Text | Executable code (read-only) | Whole program run | | Data | Global/static initialized variables | Whole program run | | BSS | Global/static uninitialized variables | Zero-initialized at startup | | Heap | Dynamically allocated memory | Until explicitly freed | | Stack | Local variables, function frames | Function scope | 3. C Memory Functions ( <stdlib.h> ) void* malloc(size_t size); // allocates uninitialized memory void* calloc(size_t n, size_t size); // allocates zero-initialized void* realloc(void* ptr, size_t new_size); // resizes void free(void* ptr); // deallocates Example:
int* arr = (int*)malloc(10 * sizeof(int)); if (arr == NULL) /* handle error */ // ... use arr ... free(arr); | Operation | Usage | |----------------------|---------------------------| | new / delete | alloc/dealloc single object | | new[] / delete[] | alloc/dealloc array | | placement new | construct in pre-allocated memory | | operator new/delete | low-level allocation hooks |
gcc -fsanitize=address -g program.c -o program ./program | Recommendation | Rationale | |----------------------------------------|----------------------------------------------| | Use std::unique_ptr / shared_ptr | Automatic lifetime management (RAII) | | Prefer std::vector , std::string | No manual new[] / delete[] needed | | Avoid raw new / delete in user code | Reduces leak/corruption risks | | Never return raw pointers to local data| Lifetimes are clear | | Use std::span (C++20) for array views| Safe bounds-checked access | | Enable compiler warnings ( -Wall -Wextra -Wpedantic ) | Catch errors early | 8. Example: RAII in C++ #include <memory> #include <vector> void safeFunction() std::unique_ptr<int[]> arr = std::make_unique<int[]>(100); // no explicit delete – automatic when arr goes out of scope
