Wide String Conversion

To work with Windows APIs, you often need to convert std::filesystem::path to a wide string (std::wstring). This is because many Windows API functions expect wide strings (UTF-16). Here’s how to perform this conversion:

Converting to Wide String

The std::filesystem::path class provides the wstring() method to obtain a wide string representation of the path:

1#include <filesystem>
2#include <iostream>
3
4int main() {
5  std::filesystem::path path{
6    R"(C:\Program Files\MyApp\file.txt)"};
7  std::wstring widePath = path.wstring();
8
9  std::wcout << L"Wide Path: " << widePath;
10}

1Wide Path: C:\Program Files\MyApp\file.txt

Using with Windows API

Here’s an example of how to use the converted wide string with a Windows API function, such as CreateFileW:

1#include <windows.h>
2
3#include <filesystem>
4#include <iostream>
5
6int main() {
7  std::filesystem::path path{R"(C:\test\file.txt)"};
8  std::wstring widePath = path.wstring();
9
10  HANDLE fileHandle = CreateFileW(
11    widePath.c_str(),       // File name
12    GENERIC_READ,           // Desired access
13    0,                      // Share mode
14    nullptr,                // Security attributes
15    OPEN_EXISTING,          // Creation disposition
16    FILE_ATTRIBUTE_NORMAL,  // Flags and attributes
17    nullptr                 // Template file handle
18  );
19
20  if (fileHandle == INVALID_HANDLE_VALUE) {
21    std::wcerr << L"Failed to open file: "
22      << GetLastError();
23  } else {
24    std::wcout << L"File opened successfully\n";
25    CloseHandle(fileHandle);
26  }
27}

1File opened successfully

Key Points

1. The wstring() Method: Use the wstring() method of std::filesystem::path to get a wide string.
2. API Compatibility: Ensure you use the wide-character version of Windows API functions (e.g., CreateFileW).
3. Error Handling: Always check the return values of API calls and handle errors appropriately.

Conclusion

Converting std::filesystem::path to std::wstring allows you to seamlessly integrate with Windows APIs that require wide strings. This method ensures your paths are correctly interpreted and managed by the system.