问题描述

我知道这已经在关于 SO 的几个问题中讨论过，但这些解决方案都没有对我有用.

我以 char* 开头，因为这是用于从 VBA 调用的 DLL，并且 char* 是 VBA 将字符串传递给 DLL 所必需的.

我需要返回一个 LPCWSTR 因为这是我试图调用的 API 函数的输入参数，我无法通过从 Unicode 切换到多字节字符集来启用转换属性窗口，因为 API 有这样的代码:

#if !defined(UNICODE) &&!defined(NOUNICODE)#error UNICODE 未定义.必须为正确的 API 参数定义 UNICODE.#万一

我试过了:

LPCWSTR convertCharArrayToLPCWSTR(char* charArray){const char* cs=charArray;wchar_t 文件名[4096] = {0};MultiByteToWideChar(0, 0, cs[1], strlen(cs[1]), filename, strlen(cs[1]));}

给出了这些错误:

错误 C2664:strlen":无法将参数 1 从const char"转换为const char *"错误 C2664:MultiByteToWideChar":无法将参数 3 从const char"转换为LPCCH"

我试过这个(相同的函数头)，大致改编自这篇文章:

size_t retVal;const char * cs = charArray;size_t 长度=strlen(cs);wchar_t * buf = new wchar_t[length]();//值初始化为 0(见下文)size_t wn = mbsrtowcs_s(&retVal,buf,20, &cs, length + 1, NULL);返回缓冲区；

编译没问题，但是当我向它传递一个示例字符串xyz.xlsx"时，mbsrtowcs_s() 将 buf 设置为空字符串:L""

那么，我该如何进行这种转换?

由于 cs 是一个 const char*，cs[1]是一个 const char.C++ 不会为您将其转换为指针，因为在大多数情况下这是没有意义的.

如果要跳过第一个字符，您可以改为使用 &cs[1] 或 cs+1.(这就是传递指向第 1 个元素的指针时所做的；在 C++ 中，索引从 0 开始.)如果意图传递整个字符串，则只需传递 cs.>

I know this has already been discussed in several questions on SO, but none of those solutions have worked for me.

I start with a char* because this is for a DLL that will be called from VBA, and char* is necessary for VBA to pass a string to the DLL.

I need to return a LPCWSTR because that's the input parameter for the API function I'm trying to call, and I can't enable casting by switching from Unicode to multi-byte character set in the Properties window, because the API has this code:

#if !defined(UNICODE) && !defined(NOUNICODE)
#error UNICODE is not defined. UNICODE must be defined for correct API arguments.
#endif

I tried this:

LPCWSTR convertCharArrayToLPCWSTR(char* charArray)
    {
        const char* cs=charArray;
        wchar_t filename[4096] = {0};
        MultiByteToWideChar(0, 0, cs[1], strlen(cs[1]), filename, strlen(cs[1]));
    }

which gave these errors:

error C2664: 'strlen' : cannot convert parameter 1 from 'const char' to 'const char *'
error C2664: 'MultiByteToWideChar' : cannot convert parameter 3 from 'const char' to 'LPCCH'

I tried this (same function header), loosely adapted from this post:

size_t retVal;
const char * cs = charArray;    
size_t length=strlen(cs);
wchar_t * buf = new wchar_t[length]();  // value-initialize to 0 (see below)
size_t wn = mbsrtowcs_s(&retVal,buf,20, &cs, length + 1, NULL);
return buf;

This compiled ok, but when I passed it an example string of "xyz.xlsx", mbsrtowcs_s() set buf to an empty string: L""

So, how do I make this conversion?

Since cs is a const char*, cs[1] is a const char. C++ won't convert it to a pointer for you, because in most cases that doesn't make sense.

You could instead say &cs[1] or cs+1 if the intent is to skip the first char. (That's what you're doing when you pass a pointer to the 1th element; in C++, indexes start at 0.) If the intent is to pass the whole string, then just pass cs.

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