What is RAII and why is it important in C++?

Question

Accepted Answer

**RAII (Resource Acquisition Is Initialization)** — tie resource lifetime to object lifetime.

```cpp
class FileHandler {
    std::FILE* file;
public:
    FileHandler(const char* name) : file(std::fopen(name, "r")) {}
    ~FileHandler() { if (file) std::fclose(file); }
    // Rule of Five applies
};
```

**Benefits:**
- Automatic cleanup on scope exit
- Exception safety (no resource leaks)
- Deterministic destruction
- Self-documenting ownership

**Modern RAII wrappers:**
- `std::unique_ptr`, `std::shared_ptr`
- `std::lock_guard`, `std::unique_lock`
- `std::fstream` for file I/O
- `std::vector` for dynamic arrays

C++: What is RAII and why is it important in C++?