# filesystem

***

**1. Create a File**

```cpp
#include <fstream>

int main() {
  std::ofstream file("myfile.txt");
  file << "Hello, world!";
  file.close();
  return 0;
}
```

**2. Write to a File**

```cpp
#include <fstream>

int main() {
  std::ofstream file("myfile.txt", std::ios::app);
  file << " This is a new line of text.";
  file.close();
  return 0;
}
```

**3. Read from a File**

```cpp
#include <fstream>

int main() {
  std::ifstream file("myfile.txt");
  std::string line;
  while (std::getline(file, line)) {
    std::cout << line << std::endl;
  }
  file.close();
  return 0;
}
```

**4. Delete a File**

```cpp
#include <filesystem>

int main() {
  std::filesystem::remove("myfile.txt");
  return 0;
}
```

**5. Create a Directory**

```cpp
#include <filesystem>

int main() {
  std::filesystem::create_directory("mydirectory");
  return 0;
}
```

**6. Delete a Directory**

```cpp
#include <filesystem>

int main() {
  std::filesystem::remove_all("mydirectory");
  return 0;
}
```

**7. Copy a File**

```cpp
#include <filesystem>

int main() {
  std::filesystem::copy("myfile.txt", "newfile.txt");
  return 0;
}
```

**8. Move a File**

```cpp
#include <filesystem>

int main() {
  std::filesystem::rename("myfile.txt", "newfile.txt");
  return 0;
}
```

**9. Check if a File Exists**

```cpp
#include <filesystem>

int main() {
  std::filesystem::exists("myfile.txt");  // returns true if file exists
  return 0;
}
```

**10. Check if a Directory Exists**

```cpp
#include <filesystem>

int main() {
  std::filesystem::exists("mydirectory");  // returns true if directory exists
  return 0;
}
```

**11. Get File Size**

```cpp
#include <filesystem>

int main() {
  std::filesystem::file_size("myfile.txt");  // returns file size in bytes
  return 0;
}
```

**12. Get File Modification Time**

```cpp
#include <filesystem>

int main() {
  std::filesystem::last_write_time("myfile.txt");  // returns file modification time
  return 0;
}
```

**13. Iterate Over Files in a Directory**

```cpp
#include <filesystem>

int main() {
  for (const auto &entry : std::filesystem::directory_iterator("mydirectory")) {
    std::cout << entry.path() << std::endl;
  }
  return 0;
}
```

**14. Iterate Over Subdirectories**

```cpp
#include <filesystem>

int main() {
  for (const auto &entry : std::filesystem::recursive_directory_iterator("mydirectory")) {
    std::cout << entry.path() << std::endl;
  }
  return 0;
}
```

**15. Create a Temporary File**

```cpp
#include <filesystem>

int main() {
  std::filesystem::path temp_file = std::filesystem::temp_directory_path() / "mytempfile.txt";
  std::ofstream file(temp_file);
  file << "Hello, world!";
  file.close();
  return 0;
}
```

**16. Read a File into Memory**

```cpp
#include <filesystem>
#include <fstream>

int

```