How to Efficiently Convert a wstring to a string in C ?

How to Efficiently Convert wstring to string in C

Converting a wstring to a string in C can be essential when working with internationalized or wide character data. This guide will explore several techniques to perform this conversion effectively.

Method 1: std::wstring_convert

Introduced in C 11, std::wstring_convert provides a simple and efficient way to convert between wstring and string. It uses an appropriate codecvt facet to handle the conversion.

#include <locale>
#include <codecvt>

// Unicode UTF-8 codecvt
std::wstring_convert<std::codecvt_utf8<wchar_t>> converter;

// Conversion
std::wstring wstr = L"Hello";
std::string str = converter.to_bytes(wstr);

Method 2: std::string Constructor Overloading

C 11 introduced a constructor for std::string that accepts a pointer to a character array. This can be used to convert a wstring to a string by converting the wide characters to narrow characters.

#include <string>

// Convert wchar_t to char using wcstombs
std::wstring wstr = L"Hello";
const wchar_t* wchar_ptr = wstr.c_str();

char* char_ptr;
size_t char_size = wcstombs(nullptr, wchar_ptr, 0);
char_ptr = new char[char_size + 1];
wcstombs(char_ptr, wchar_ptr, char_size + 1);

// Construct std::string from char array
std::string str(char_ptr);

Method 3: std::stringstream

Although not recommended, std::stringstream can be used to convert a wstring to a string, but it requires extra steps to convert the wstringstream to a string.

#include <sstream>

std::wstring wstr = L"Hello";
std::wstringstream wss(wstr);

// Extract std::string from std::wstringstream
std::string str;
wss >> str;

Conclusion

std::wstring_convert and std::string constructor overloading provide efficient and direct methods for converting wstring to string. While std::stringstream can be used, it is less optimal. The choice of conversion method depends on the specific requirements and preferences of the implementation.

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