无法从"const char *"转换为"LPCTSTR" [英] cannot convert from 'const char *' to 'LPCTSTR'

问题描述

我正在尝试将字符串转换为'LPCTSTR'，但是，出现以下错误.

I'm trying to convert string to 'LPCTSTR', but, i got following error.

错误:

cannot convert from 'const char *' to 'LPCTSTR'

代码:

std::string str = "helloworld";
LPCTSTR lp = str.c_str();

也尝试过:

LPCTSTR lp = (LPCTSTR)str.c_str();

但是，打印垃圾值.

推荐答案

LPCTSTR表示(指向常量TCHAR字符串的长指针).

LPCTSTR means (long pointer to constant TCHAR string).

根据您的项目设置，TCHAR可以为wchar_t或char.

A TCHAR can either be wchar_t or char based on what your project settings are.

如果在项目设置的常规"选项卡中，字符集为使用多字节字符集"，则TCHAR是char的别名.但是，如果将其设置为使用Unicode字符集"，则TCHAR是wchar_t的别名.

If, in your project settings, in the "General" tab, your character set is "Use Multi-byte character set" then TCHAR is an alias for char. However, if it's set to "Use Unicode character set" then TCHAR is an alias for wchar_t instead.

您必须使用Unicode字符集，因此:

You must be using the Unicode character set, so:

LPCTSTR lp = str.c_str();

是现实中的

// c_str() returns const char*
const wchar_t* lp = str.c_str();

这就是为什么出现错误的原因:

This is why you're getting the error:

无法从'const char *'转换为'LPCTSTR'

cannot convert from 'const char *' to 'LPCTSTR'

您的行:

LPCTSTR lp = (LPCTSTR)str.c_str();

是现实中的

const wchar_t* lp = (const wchar_t*) std.c_str(); 

在std::string中，字符是单个字节，指向它们的wchar_t*会期望每个字符都是2+字节.这就是为什么您会得到无意义的值.

In a std::string, the chars are single bytes, having a wchar_t* point to them will expect that each character is 2+ bytes instead. That's why you're getting nonsense values.

最好的做法是按照Hans Passant的建议-不要使用基于TCHAR的typedef.在您的情况下，请执行以下操作:

The best thing to do would be as Hans Passant suggested - not to use typedefs based on TCHAR. In your case, do this instead:

std::string str = "helloworld";
const char* lp = str.c_str(); // or
LPCSTR lp = str.c_str();

如果要使用Windows称为Unicode的宽字符，则可以执行以下操作:

If you want to use wide chars, which Windows calls Unicode, then you can do this:

std::wstring wstr = L"helloword";
const wchar_t* lp = wstr.c_str() // or
LPCWSTR lp = wstr.c_str();

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