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Use signed or unsigned char in constructing CString?


Use signed or unsigned char in constructing CString?

By : Milan Vasovic
Date : November 22 2020, 07:01 PM
Any of those help LPCSTR is just const char*, not const signed char*. char is signed or unsigned depending on compiler implementation, but char, signed char, and unsigned char are 3 distinct types for purposes of overloading. String literals in C++ are of type const char[], so CStringT("Hello") will always use the LPCSTR constructor, never the unsigned char* constructor.
sqlite3_column_text(...) returns unsigned char* because it returns UTF-8 encoded text. I don't know what the unsigned char* constructor of CStringT actually does (it has something to do with MBCS strings), but the LPCSTR constructor performs a conversion from ANSI to UNICODE using the user's default locale. That would destroy UTF-8 text that contains non-ASCII characters.
code :


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How does one convert from CString to unsigned char* with Unicode?

How does one convert from CString to unsigned char* with Unicode?


By : simon
Date : March 29 2020, 07:55 AM
should help you out I'm trying to do something simple here. When I execute the following code in Visual Studio 2008 using the unicode character set, xmlString is correct. , I find the simplest is to use the CStringA constructor, like this:
code :
    CString xmlString;
    xmlString.Format( _T("<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?><gateway><config-read><%s /></config-read></gateway>"), "test");

    printf("%s\n",xmlString );  // fails "<"

    //unsigned char * ucStr = reinterpret_cast<unsigned char *> (xmlString.GetBuffer());

    CStringA ucStr( xmlString );

    printf("%s\n",ucStr );   // works!
Function overloading for char, signed char or unsigned char parameter type in terms of compiling template

Function overloading for char, signed char or unsigned char parameter type in terms of compiling template


By : Syed Anuar
Date : March 29 2020, 07:55 AM
wish helps you If you want a type trait like that, you will have to make one yourself:
code :
template <typename T>
struct is_char
{
    static const bool value = std::is_same<T, char>::value ||
            std::is_same<T, signed char>::value ||
            std::is_same<T, unsigned char>::value;
};

template <typename T>
void f(T t, typename std::enable_if<is_char<T>::value>::type* = 0)
{
} 
C/C++ underlying representation of char, unsigned char and signed char

C/C++ underlying representation of char, unsigned char and signed char


By : JonSnows
Date : March 29 2020, 07:55 AM
hope this fix your issue In general case it is not correct to say that the pattern is the same, if the range of signed char does not cover 240. If 240 is out of range, the result of this overflowing initialization is implementation-defined (and may result in a signal, see 6.3.1.3/3). The same applies to char initialization if it is signed.
The language guarantees matching representations only for the common part of the ranges of signed char and unsigned char. E.g. this is guaranteed to produce the same pattern
code :
char c = 10;
unsigned char c = 10;
signed char c = 10;
How to correctly convert unsigned char to CString and once again, reversely convert to the result of CString to unsigned

How to correctly convert unsigned char to CString and once again, reversely convert to the result of CString to unsigned


By : Brandon Tao
Date : March 29 2020, 07:55 AM
To fix this issue Conversion to CString is pretty easy, just pass the unsigned char* to the c'tor. Conversion from CString to unsigned char* is a little more work, see below.
code :
unsigned char orig[] = "hello world";
std::cout << orig << " (unsigned char *)" << std::endl;

// Convert to a CString
CString cstring(orig);
std::cout << cstring << " (CString)" << std::endl;

// Convert to a unsigned char*
const size_t newsize = (cstring.GetLength() + 1);
unsigned char* nstring = new unsigned char[newsize];
strcpy_s((char*)nstring, newsize, cstring);
std::cout << nstring << " (unsigned char*)" << std::endl;
Convert ATL::CString to std::vector<unsigned char>

Convert ATL::CString to std::vector<unsigned char>


By : Yuzhou
Date : March 29 2020, 07:55 AM
I wish this helpful for you It's likely that TCHAR on your platform is wchar_t, so is two bytes, so CString is really a container of wide chars. What you want is to do a conversion instead of a byte-wise copy:
code :
inline void Str2Data(std::vector<unsigned char> &To, const CString &From)
{
    if (!From.IsEmpty()) {
        To.resize(From.GetLength());
        std::transform(From.GetString(), 
                       From.GetString() + From.GetLength(),
                       To.begin(),
                       [](TCHAR c) { return static_cast<unsigned char>(c); });
    }
    else {
        To.clear();
    }
}
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