C++ 无法将参数 1 从“char *”转换为“LPCWSTR”

cannot convert parameter 1 from 'char *' to 'LPCWSTR'

提问by dactz

Im trying to load a BMP file

我正在尝试加载 BMP 文件

AUX_RGBImageRec *LoadBMP(char *Filename)  // Loads A Bitmap Image
{
    FILE *File=NULL;                      // File Handle

    if (!Filename)                        // Make Sure A Filename Was Given
    {
        return NULL;                      // If Not Return NULL
    }

    File=fopen(Filename,"r");             // Check To See If The File Exists

    if (File)                             // Does The File Exist?
    {
        fclose(File);                     // Close The Handle
        return auxDIBImageLoad(Filename); // Load The Bitmap And Return A Pointer
    }

    return NULL;                          // If Load Failed Return NULL
}

this has come from an example however i'm now getting the error

这是来自一个例子但是我现在收到错误

error C2664: 'auxDIBImageLoadW' : cannot convert parameter 1 from 'char *' to 'LPCWSTR'

错误 C2664：“auxDIBImageLoadW”：无法将参数 1 从“char *”转换为“LPCWSTR”

how could I correct this?

我怎么能纠正这个？

回答by Paul Groke

You're compiling your application with Character-Set set to UNICODE (Project Settings -> Configuration Options -> General). Windows header files use #defines to "map" function names to either nameA (for multi-byte strings) or nameW (for unicode strings).

您正在使用字符集设置为 UNICODE（项目设置 -> 配置选项 -> 常规）编译应用程序。Windows 头文件使用 #defines 将函数名称“映射”到 nameA（对于多字节字符串）或 nameW（对于 unicode 字符串）。

That means somewhere in a header file there will be a #define like this

这意味着在头文件中的某处会有这样的#define

#define auxDIBImageLoad auxDIBImageLoadW

So you're not actually calling auxDIBImageLoad(there is no function with that name), you're calling auxDIBImageLoadW. And auxDIBImageLoadWexpects a unicode string (wchar_t const*). You're passing a multi-byte string (char const*).

因此，您实际上并不是在调用auxDIBImageLoad（没有具有该名称的函数），而是在调用auxDIBImageLoadW. 并auxDIBImageLoadW期望一个 unicode 字符串 ( wchar_t const*)。您正在传递一个多字节字符串 ( char const*)。

You can do one of the following

您可以执行以下操作之一

• change your project to use multi-byte character set (-> project settings)
• explicitly call the multi-byte version of the function by replacing auxDIBImageLoadwith auxDIBImageLoadA
• change your LoadBMPfunction to accept a unicode string itself
• convert the string to unicode inside LoadBMP

• 更改您的项目以使用多字节字符集（-> 项目设置）
• 通过替换auxDIBImageLoad为显式调用函数的多字节版本auxDIBImageLoadA
• 更改您的LoadBMP函数以接受 unicode 字符串本身
• 将字符串转换为里面的 unicode LoadBMP

I'd recommend either changing LoadBMPto accept a unicode string itself or calling auxDIBImageLoadAdirectly (in that order). Changing the project settings might be OK if it doesn't break a lot of other code. I would notsuggest converting the string though, since it's unnecessary. Calling auxDIBImageLoadAdirectly is far easier, and the result is the same.

我建议要么更改LoadBMP为接受 unicode 字符串本身，要么auxDIBImageLoadA直接调用（按该顺序）。如果更改项目设置不会破坏很多其他代码，那么它可能没问题。我不建议转换字符串，因为它是不必要的。auxDIBImageLoadA直接调用要容易得多，结果是一样的。

回答by ildjarn

You have a few options:

您有几个选择：

• Change the 'character set' option in your project settings from 'Unicode' to 'Not Set'
• Call auxDIBImageLoadAinstead of auxDIBImageLoad
• Change Filename's type from char*to wchar_t*
• Use std::mbstowcsto convert Filename from a char*to a wchar_t*

• 将项目设置中的“字符集”选项从“Unicode”更改为“未设置”
• 调用auxDIBImageLoadA而不是auxDIBImageLoad
• 将Filename类型从更改char*为wchar_t*
• 使用std::mbstowcs到文件名从转换char*到wchar_t*

回答by skimobear

Looks like your trying to use two different character sets. 'char ' is the typical ANSI and LPCWSTR is the wide character (i.e. unicode). If you would like to use charchange the 'Character Set' property in your project setting to 'No Set'.

看起来您尝试使用两种不同的字符集。'char ' 是典型的 ANSI，LPCWSTR 是宽字符（即 unicode）。如果您想使用 char，请将项目设置中的“Character Set”属性更改为“No Set”。

回答by Slavy Mihov

Try using MultiByteToWideChar()the following way:

尝试按以下方式使用MultiByteToWideChar()：

void main(int argc, char* argv[])
{
 ...
 wchar_t filename[4096] = {0};
 MultiByteToWideChar(0, 0, argv[1], strlen(argv[1]), filename, strlen(argv[1]));

 // RenderFile() requires LPCWSTR (or wchar_t*, respectively)
 hr = pGraph->RenderFile(filename, NULL);
 ...
}

回答by Cole W

Convert the character array to a LPCWSTR. You can see this in the 2nd guys post here

将字符数组转换为 LPCWSTR。您可以在此处的第二个家伙中看到这一点