This library contains a set of classes for working with strings in UTF-8 format, as well as functions for converting strings in utf8, ANSI, utf16, utf32 formats.

1. Conversion from/to UTF8
2. utf8::String class
3. utf8::Char class
4. Utf8Ptr and AnsiPtr Classes

The most commonly used format conversion operations are converting from ANSI encoding (on Windows), as well as from a Unicode string (on Windows it is a utf-16 encoded string; on Posix systems it is utf-32). This library allows to solve these problems by calling one of the conversion functions:

const wchar_t* unicode_str = L"тЕкст1 王明 Mötley Crüe";

std::string utf8_str = utf8::WstringToUtf8(unicode_str);
std::wstring unicode_str2 = utf8::Utf8ToWstring(utf8_str.c_str());
assert(wcscmp(unicode_str, unicode_str2.c_str()) == 0);

#ifdef _WIN32
 WIN32_FIND_DATAA fd;
 HANDLE h = FindFirstFileA(mask, &fd);
 if (h != INVALID_HANDLE_VALUE)
 {
   std::string u8name = utf8::AnsiToUtf8(fd.cFileName);
   FindClose(h);
 }
#endif

In a utf-8 string, a character can be encoded with one, two, or three bytes (https://en.wikipedia.org/wiki/UTF-8). Thus, in general, the length of a string in characters and the length of a string in bytes are different values. Therefore, STL classes such as std::string are not suitable for a number of operations (for example, searching and extracting substrings). This library offers the utf8::String class for working with utf8 strings. This class is similar to std::string in many ways, but correctly implements all operations on working with a string in utf8

utf8::String u8str(u8"Абв");
printf("Number of characters: %zu\n", u8str.length());  // 3 characters
printf("Size in bytes: %zu\n", u8str.size()); // 6 bytes

utf8::Char ch(L'Ж');
u8str.ReplaceAt(1, ch); // now u8str contains "АЖв"

One of the problems when working with characters in a national encoding is the conversion of the character case. The utf8 library implements these methods for both Windows and Linux. Thus, the ToLowerCase and ToUpperCase methods of the utf8::String class are able to correctly perform such a conversion and do not require changes in С locale.

Utf-8 characters can occupy more than one byte. Thus, the built-in C char type is not fully suitable for storing utf8 characters. Since some of the utf8::String class methods accept or return a single character, the library defines a special type for storing a single character - utf8::Char.

As is known, a character is encoded by 8 bits in several encodings at once. This is the Utf8 encoding, and the ANSI and latin encoding. In the C code, all this corresponds to const char*. In order to be able to distinguish these types when passing a pointer to a string to the methods of the utf8::String class, the helper classes Utf8Ptr and AnsiPtr are introduced.

utf8::String u8str(AnsiPtr("текст в кодировке ANSI"));

Understanding the type of the string received as input, the utf8::String class performs the appropriate conversion