Convert to wstring

Converting a std::string to a std::wstring involves converting between narrow (char) and wide (wchar_t) characters. This is often necessary when dealing with different character encodings, such as ASCII and Unicode.

Basic Conversion

To convert a std::string to a std::wstring, you need to handle the conversion of each character. The simplest way to do this is to use the std::wstring constructor that takes a std::string as an argument. For example:

1#include <iostream>
2#include <string>
3
4int main() {
5  std::string NarrowString{"Hello, World!"};
6  std::wstring WideString{
7    NarrowString.begin(), NarrowString.end()
8  };  
9
10  std::wcout << WideString;
11}

1Hello, World!

Using std::mbstowcs

For more control over the conversion, especially with different locales, you can use std::mbstowcs which stands for multi-byte string to wide-character string. For example:

1#include <iostream>
2#include <string>
3#include <cwchar>
4#include <vector>
5
6int main() {
7  std::string NarrowString{"Hello, World!"};
8  std::vector<wchar_t> WideString(
9    NarrowString.size() + 1
10  );
11
12  size_t convertedChars = 0;
13
14#ifdef _WIN32
15  mbstowcs_s(
16    &convertedChars, &WideString[0],
17    WideString.size(), NarrowString.c_str(),
18    NarrowString.size()
19  );
20#else
21  convertedChars = mbstowcs(
22    &WideString[0],
23    NarrowString.c_str(),
24    WideString.size()
25  );
26#endif
27
28  std::wcout << &WideString[0];
29}

1Hello, World!

Considerations

• Locale: The conversion depends on the current C locale. You can set the locale using std::setlocale().
• Encoding: Ensure that the encoding of the std::string is compatible with the conversion process.

Advanced Conversion

For more complex scenarios, such as converting between different character sets, consider using libraries like ICU (International Components for Unicode) or Boost.Locale.

1#include <boost/locale.hpp>
2#include <iostream>
3#include <string>
4
5int main() {
6  std::string NarrowString{"Hello, World!"};
7
8  std::wstring WideString =
9    boost::locale::conv::to_utf<wchar_t>(
10      NarrowString, "UTF-8"
11    );  
12
13  std::wcout << WideString;
14}

1Hello, World!

Converting between std::string and std::wstring allows you to handle different text encodings, making your applications more versatile in handling international text.