問題描述

我在我的 C++ 代碼中遇到一個我無法理解的錯誤.精簡后的代碼位在這里:

I'm getting an error in my C++ code that I can't quite make sense of. The stripped down code bits are here:

RS232Handle=OpenRS232("COM1", 9600);

HANDLE OpenRS232(const char* ComName, DWORD BaudRate)
{
    ComHandle=CreateFile(ComName, GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
}

我收到以下錯誤:

error: cannot convert 'const char*' to 'LPCWSTR {aka const wchar_t*}' for argument '1' to 'void* CreateFileW(LPCWSTR, DWORD, DWORD, LPSECURITY_ATTRIBUTES, DWORD, DWORD, HANDLE)'
     ComHandle=CreateFile(ComName, GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

代碼取自 VS 代碼，我現(xiàn)在使用 Qt creator.

The code was taken from VS code and I am now using Qt creator.

我該如何解決這個問題?謝謝！

How can I fix this issue? Thanks!

推薦答案

Windows CreateFile 函數(shù)實際上是一個擴展為以下之一的宏:

The Windows CreateFile function is actually a macro that expands to one of:

• CreateFileA，它采用 const char*
類型的文件路徑
• CreateFileW，它采用 const wchar_t* 類型的文件路徑.

• CreateFileA, which takes a file path of type const char*
• CreateFileW, which takes a file path of type const wchar_t*.

(Windows API 中大多數(shù)采用字符串的函數(shù)也是如此.)

(The same is true for most of the functions in the Windows API that take a string.)

您聲明了參數(shù) const char* ComName，但顯然編譯時定義了 UNICODE，因此它調(diào)用了 W 版本的功能.沒有從 const wchar_t* 到 const char* 的自動轉(zhuǎn)換，因此出現(xiàn)錯誤.

You're declaring the parameter const char* ComName, but apparently compiling with UNICODE defined, so it's calling the W version of the function. There's no automatic conversion from const wchar_t* to const char*, hence the error.

您的選擇是:

1. 將函數(shù)參數(shù)更改為 UTF-16 (const wchar_t*) 字符串.
2. 保留 char* 參數(shù)，但讓您的函數(shù)使用 MultiByteToWideChar.
3. 顯式調(diào)用 CreateFileA 而不是 CreateFile.
4. 在不使用 UNICODE 的情況下編譯您的程序，以便宏默認擴展為 A 版本.
5. 綁架一位著名的 Microsoft 開發(fā)人員并強迫他閱讀UTF-8 Everywhere，直到他同意讓 Windows 完全支持 UTF-8 作為ANSI"代碼頁，從而使各地的 Windows 開發(fā)人員擺脫這種寬字符的束縛.

1. Change the function parameter to a UTF-16 (const wchar_t*) string.
2. Keep the char* parameter, but have your function explicitly convert it to a UTF-16 string with a function like MultiByteToWideChar.
3. Explicitly call CreateFileA instead of CreateFile.
4. Compile your program without UNICODE, so that the macros expand to the A versions by default.
5. Kidnap a prominent Microsoft developer and force him to read UTF-8 Everywhere until he agrees to have Windows fully support UTF-8 as an "ANSI" code page, thus freeing Windows developers everywhere from this wide-character stuff.

我不知道是否涉及綁架，但 Windows 10 1903 終于添加了支持 對于 UTF-8 作為 ANSI 代碼頁.

I don't know if a kidnapping was involved, but Windows 10 1903 finally added support for UTF-8 as an ANSI code page.

這篇關(guān)于無法將“const char*"轉(zhuǎn)換為“LPCWSTR {aka const wchar_t*}"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(wǎng)！