[英]How do I convert from _TCHAR * to char * when using C++ variable-length args?
We need to pass a format _TCHAR * string, and a number of char * strings into a function with variable-length args: 我们需要将一个格式_TCHAR *字符串和一些char *字符串传递给一个带有可变长度args的函数:
inline void FooBar(const _TCHAR *szFmt, const char *cArgs, ...) {
//...
}
So it can be called like so: 所以它可以这样调用:
char *foo = "foo";
char *bar = "bar";
LogToFileA(_T("Test %s %s"), foo, bar);
Obviously a simple fix would be to use _TCHAR instead of char, but we don't have that luxury unfortunately. 显然,一个简单的解决方法是使用_TCHAR而不是char,但遗憾的是我们并没有那么奢侈。
We need to use this with va_start, etc so we can format a string: 我们需要将它与va_start等一起使用,以便我们可以格式化一个字符串:
va_list args;
_TCHAR szBuf[BUFFER_MED_SIZE];
va_start(args, cArgs);
_vstprintf_s(szBuf, BUFFER_MED_SIZE, szFmt, args);
va_end(args);
Unfortunately we cannot use this because it give us this error: 不幸的是我们不能使用它,因为它给了我们这个错误:
Unhandled exception at 0x6a0d7f4f (msvcr90d.dll) in foobar.exe:
0xC0000005: Access violation reading location 0x2d86fead.
I'm thinking we need to convert our char * to _TCHAR * - but how? 我想我们需要将我们的char *转换为_TCHAR * - 但是如何?
Use %hs or %hS instead of %s. 使用%hs或%hS代替%s。 That will force the parameters to be interpretted as char* in both Ansi and Unicode versions of printf()-style functions, ie:
这将强制参数在Ansi和Unicode版本的printf() - 样式函数中被解释为char *,即:
inline void LogToFile(const _TCHAR *szFmt, ...)
{
va_list args;
TCHAR szBuf[BUFFER_MED_SIZE];
va_start(args, szFmt);
_vstprintf_s(szBuf, BUFFER_MED_SIZE, szFmt, args);
va_end(args);
}
{
char *foo = "foo";
char *bar = "bar";
LogToFile(_T("Test %hs %hs"), foo, bar);
}
Usually it looks like the following: 通常它看起来如下:
char *foo = "foo";
char *bar = "bar";
#ifdef UNICODE
LogToFileW( L"Test %S %S", foo, bar); // big S
#else
LogToFileA( "Test %s %s", foo, bar);
#endif
Your question is not completely clear. 你的问题并不完全清楚。 How your function is implemented and how do you use it?
您的功能如何实现以及如何使用它?
Here was my solution - I welcome suggestions for improvement! 这是我的解决方案 - 我欢迎改进建议!
inline void FooBar(const _TCHAR *szFmt, const char *cArgs, ...) {
va_list args;
_TCHAR szBuf[BUFFER_MED_SIZE];
// Count the number of arguments in the format string.
const _TCHAR *at = _tcschr(szFmt, '%');
int argCount = 0;
while(at) {
argCount++;
at = _tcschr(at + 1, '%');
}
CA2W *ca2wArr[100];
LPWSTR szArgs[100];
va_start(args, cArgs);
for (int i = 1; i < argCount + 1; i++) {
CA2W *ca2w = new CA2W(cArgs);
szArgs[i] = ca2w->m_psz;
ca2wArr[i] = ca2w;
cArgs = va_arg(args, const char *);
}
va_end(args);
// Use the new array we just created (skips over first element).
va_start(args, szArgs[0]);
_vstprintf_s(szBuf, BUFFER_MED_SIZE, szFmt, args);
va_end(args);
// Free up memory used by CA2W objects.
for (int i = 1; i < argCount + 1; i++) {
delete ca2wArr[i];
}
// ... snip ... - code that uses szBuf
}
this is something I have used before to convert a TCHAR to char, hope it helps, although I wasn't really looking for optimization, so it's not the fastest way.. but it worked! 这是我之前用过将TCHAR转换为char的东西,希望它有所帮助,虽然我并不是真的在寻找优化,所以它不是最快的方式......但它有效!
TCHAR tmp[255];
::GetWindowText(hwnd, tmp, 255);
std::wstring s = tmp;
//convert from wchar to char
const wchar_t* wstr = s.c_str();
size_t wlen = wcslen(wstr) + 1;
char newchar[100];
size_t convertedChars = 0;
wcstombs_s(&convertedChars, newchar, wlen, wstr, _TRUNCATE);
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