問題描述

有什么方法可以利用 Win32 API 中的文件創建標志，例如 FILE_FLAG_DELETE_ON_CLOSE 或 FILE_FLAG_WRITE_THROUGH，如此處所述http://msdn.microsoft.com/en-us/library/aa363858(VS.85).aspx ，然后將該句柄強制轉換為 std::ofstream ?

Is there any way to take advantage of the file creation flags in the Win32 API such as FILE_FLAG_DELETE_ON_CLOSE or FILE_FLAG_WRITE_THROUGH as described here http://msdn.microsoft.com/en-us/library/aa363858(VS.85).aspx , but then force that handle into a std::ofstream?

ofstream 的接口顯然是平臺無關的；我想在幕后"中強制執行一些平臺相關的設置.

The interface to ofstream is obviously platform independent; I'd like to force some platform dependent settings in 'under the hood' as it were.

推薦答案

可以將 C++ std::ofstream 附加到 Windows 文件句柄.以下代碼適用于 VS2008:

It is possible to attach a C++ std::ofstream to a Windows file handle. The following code works in VS2008:

HANDLE file_handle = CreateFile(
    file_name, GENERIC_WRITE,
    0, NULL, CREATE_ALWAYS,
    FILE_ATTRIBUTE_NORMAL, NULL);

if (file_handle != INVALID_HANDLE_VALUE) {
    int file_descriptor = _open_osfhandle((intptr_t)file_handle, 0);

    if (file_descriptor != -1) {
        FILE* file = _fdopen(file_descriptor, "w");

        if (file != NULL) {
            std::ofstream stream(file);

            stream << "Hello World
";

            // Closes stream, file, file_descriptor, and file_handle.
            stream.close();

            file = NULL;
            file_descriptor = -1;
            file_handle = INVALID_HANDLE_VALUE;
        }
}

這適用于 FILE_FLAG_DELETE_ON_CLOSE，但 FILE_FLAG_WRITE_THROUGH 可能沒有預期的效果，因為數據將被 std::ofstream 對象緩沖，而不是直接寫入磁盤.但是，當調用 stream.close() 時，緩沖區中的任何數據都將刷新到操作系統.

This works with FILE_FLAG_DELETE_ON_CLOSE, but FILE_FLAG_WRITE_THROUGH may not have the desired effect, as data will be buffered by the std::ofstream object, and not be written directly to disk. Any data in the buffer will be flushed to the OS when stream.close() is called, however.

這篇關于我可以使用 CreateFile，但將句柄強制轉換為 std::ofstream 嗎?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！