C++ std::string Conversion to std::wstring
Example
In C++, sequences of characters are represented by specializing the std::basic_string class with a native character type. The two major collections defined by the standard library are std::string and std::wstring:
-
std::stringis built with elements of typechar -
std::wstringis built with elements of typewchar_t
To convert between the two types, use wstring_convert:
#include <string>
#include <codecvt>
#include <locale>
std::string input_str = "this is a -string-, which is a sequence based on the -char- type.";
std::wstring input_wstr = L"this is a -wide- string, which is based on the -wchar_t- type.";
// conversion
std::wstring str_turned_to_wstr = std::wstring_convert<std::codecvt_utf8<wchar_t>>().from_bytes(input_str);
std::string wstr_turned_to_str = std::wstring_convert<std::codecvt_utf8<wchar_t>>().to_bytes(input_wstr);
In order to improve usability and/or readability, you can define functions to perform the conversion:
#include <string>
#include <codecvt>
#include <locale>
using convert_t = std::codecvt_utf8<wchar_t>;
std::wstring_convert<convert_t, wchar_t> strconverter;
std::string to_string(std::wstring wstr)
{
return strconverter.to_bytes(wstr);
}
std::wstring to_wstring(std::string str)
{
return strconverter.from_bytes(str);
}
Sample usage:
std::wstring a_wide_string = to_wstring("Hello World!");
That's certainly more readable than std::wstring_convert<std::codecvt_utf8<wchar_t>>().from_bytes("Hello World!").
Please note that char and wchar_t do not imply encoding, and gives no indication of size in bytes. For instance, wchar_t is commonly implemented as a 2-bytes data type and typically contains UTF-16 encoded data under Windows (or UCS-2 in versions prior to Windows 2000) and as a 4-bytes data type encoded using UTF-32 under Linux. This is in contrast with the newer types char16_t and char32_t, which were introduced in C++11 and are guaranteed to be large enough to hold any UTF16 or UTF32 "character" (or more precisely, code point) respectively.
