C语言 如何从 WSAGetLastError() 检索错误字符串？
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How do I retrieve an error string from WSAGetLastError()?
提问by Drew Hall
I'm porting some sockets code from Linux to Windows.
我正在将一些套接字代码从 Linux 移植到 Windows。
In Linux, I could use strerror()to convert an errno code into a human-readable string.
在 Linux 中，我可以strerror()将 errno 代码转换为人类可读的字符串。
MSDN documentation shows equivalent strings for each error code returned from WSAGetLastError(), but I don't see anything about how to retrieve those strings. Will strerror()work here too?
MSDN 文档显示了从 返回的每个错误代码的等效字符串WSAGetLastError()，但我没有看到有关如何检索这些字符串的任何信息。也会strerror()在这里工作吗？
How can I retrieve human-readable error strings from Winsock?
如何从 Winsock 检索人类可读的错误字符串？
采纳答案by CB Bailey
As the documentation for WSAGetLastErrorsays you can use FormatMessageto obtain a text version of the error message.
正如文档WSAGetLastError所说，您可以使用它FormatMessage来获取错误消息的文本版本。
You need to set FORMAT_MESSAGE_FROM_SYSTEMin the dwFlagsparameter and pass the error code as the dwMessageparameter.
您需要FORMAT_MESSAGE_FROM_SYSTEM在dwFlags参数中设置并传递错误代码作为dwMessage参数。
回答by mxcl
wchar_t *s = NULL;
FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
NULL, WSAGetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPWSTR)&s, 0, NULL);
fprintf(stderr, "%S\n", s);
LocalFree(s);
回答by Stan Sieler
A slightly simpler version of mxcl's answer, which removes the need for malloc/free and the risks implicit therein, and which handles the case where no message text is available (since Microsoft doesn't document what happens then):
mxcl 答案的一个稍微简单的版本，它消除了对 malloc/free 的需要以及其中隐含的风险，并处理没有消息文本可用的情况（因为 Microsoft 没有记录当时发生的情况）：
int
err;
char
msgbuf [256]; // for a message up to 255 bytes.
msgbuf [0] = '##代码##'; // Microsoft doesn't guarantee this on man page.
err = WSAGetLastError ();
FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, // flags
NULL, // lpsource
err, // message id
MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT), // languageid
msgbuf, // output buffer
sizeof (msgbuf), // size of msgbuf, bytes
NULL); // va_list of arguments
if (! *msgbuf)
sprintf (msgbuf, "%d", err); // provide error # if no string available
