C++ 在各种字符串类型之间相互转换
本文最后更新于：2023年2月8日 晚上
简述
最近在写 MFC 程序的过程中经常遇到不同字符串类型间的转换，也是在查资料的过程中意外发现了微软的一篇文档：如何：在各种字符串类型之间进行转换。介绍的相当全面，即便是没有提及的基本也可以通过多次转换得到，本文将比较常用的一些转换提炼成代码片段，以便以后查阅☠
多字节 <==> 宽字符
1. MultiByteToWideChar
官方文档：MultiByteToWideChar function (stringapiset.h)
int MultiByteToWideChar(
UINT CodePage,
DWORD dwFlags,
_In_NLS_string_(cbMultiByte)LPCCH lpMultiByteStr,
int cbMultiByte,
LPWSTR lpWideCharStr,
int cchWideChar
);宽字符字符串（wchar_t * or wstring）转多字节字符串（string）
std::string wc2mb(const wchar_t* buffer, int len)
{
int nChars = WideCharToMultiByte(CP_UTF8, 0, buffer, len, NULL, 0, NULL, NULL);
if (nChars == 0) return "";
std::string str;
str.resize(nChars);
WideCharToMultiByte(CP_UTF8, 0, buffer, len, const_cast<char*>(str.c_str()), nChars, NULL, NULL);
return str;
}
std::string wc2mb(const std::wstring& str)
{
return wc2mb(str.c_str(), (int)str.size());
}2. WideCharToMultiByte
官方文档：WideCharToMultiByte function (stringapiset.h)
int WideCharToMultiByte(
UINT CodePage,
DWORD dwFlags,
_In_NLS_string_(cchWideChar)LPCWCH lpWideCharStr,
int cchWideChar,
LPSTR lpMultiByteStr,
int cbMultiByte,
LPCCH lpDefaultChar,
LPBOOL lpUsedDefaultChar
);多字节字符串（char *）转宽字符字符串（wchar_t *）
wchar_t* mb2wc(char * chs)
{
int bufSize = MultiByteToWideChar(CP_UTF8, 0, chs, -1, NULL, 0);
wchar_t* wcs = new wchar_t[bufSize];
MultiByteToWideChar(CP_UTF8, 0, chs, -1, wcs, bufSize);
return wcs;
}从 char * 转换
1. To wchar_t *
char *orig = "Hello, World!";
size_t newsize = strlen(orig) + 1; // 14
wchar_t * wcstring = new wchar_t[newsize];
size_t convertedChars = 0;
mbstowcs_s(&convertedChars, wcstring, newsize, orig, _TRUNCATE); // Required <stdlib.h>2. To _bstr_t
char *orig = "Hello, World!";
_bstr_t bstrt(orig);3. To CComBSTR
char *orig = "Hello, World!";
CComBSTR ccombstr(orig);
CW2A printstr(ccombstr);
cout << printstr << endl;4. To CStringA
char *orig = "Hello, World!";
CStringA cstringa(orig);5. To CStringW
char *orig = "Hello, World!";
CStringW cstring(orig);6. To string
char *orig = "Hello, World!";
string basicstring(orig);7. To System::String
char *orig = "Hello, World!";
String ^systemstring = gcnew String(orig);
delete systemstring;从 wchar_t * 转换
1. To char *
wchar_t *orig = _T("Hello, World!");
size_t origsize = wcslen(orig) + 1; // 14
size_t newsize = origsize * 2; // 28, 宽字符占2个字节
char *nstring = new char[origsize];
size_t convertedChars = 0;
wcstombs_s(&convertedChars, nstring, newsize, orig, _TRUNCATE); // Put a copy of the converted string into nstring
_mbscat_s((unsigned char*)nstring, newsize, (unsigned char*)strConcat); // append the type of string to the new string.2. To _bstr_t
wchar_t *orig = _T("Hello, World!");
_bstr_t bstrt(orig);3. To CComBSTR
wchar_t *orig = _T("Hello, World!");
CComBSTR ccombstr(orig);
CW2A printstr(ccombstr);
cout << printstr << endl;
wcout << (LPCTSTR) ccombstr << endl; // 更简单4. To CStringA
wchar_t *orig = _T("Hello, World!");
CStringA cstringa(orig);5. To CStringW
wchar_t *orig = _T("Hello, World!");
CStringW cstring(orig);6. To wstring
wchar_t *orig = _T("Hello, World!");
wstring basicstring(orig);7. To System::String
wchar_t *orig = _T("Hello, World!");
String ^systemstring = gcnew String(orig);
delete systemstring;从 CString 转换
1. CStringA to char *
CStringA origa("Hello, World!");
const size_t newsizea = (origa.GetLength() + 1);
char *nstringa = new char[newsizea];
strcpy_s(nstringa, newsizea, origa);2. CStringW to char *
CStringW origw("Hello, World!");
const size_t newsizew = (origw.GetLength() + 1) * 2;
char *nstringw = new char[newsizew];
size_t convertedCharsw = 0;
wcstombs_s(&convertedCharsw, nstringw, newsizew, origw, _TRUNCATE );3. CStringA to wchar_t *
CStringA origa("Hello, World!");
const size_t newsizea = (origa.GetLength() + 1);
size_t convertedCharsa = 0;
wchar_t *wcstring = new wchar_t[newsizea];
mbstowcs_s(&convertedCharsa, wcstring, newsizea, origa, _TRUNCATE);4. CStringW to wchar_t *
CStringW origw("Hello, World!");
const size_t newsizew = (origw.GetLength() + 1) * 2;
wchar_t *n2stringw = new wchar_t[newsizew];
wcscpy_s( n2stringw, newsizew, origw );5. CStringA to _bstr_t
CStringA origa("Hello, World!");
_bstr_t bstrt(origa);6. CStringW to _bstr_t
CStringW origw("Hello, World!");
bstr_t bstrtw(origw);7. CStringA to CComBSTR
CStringA origa("Hello, World!");
CComBSTR ccombstr(origa);
CW2A printstr(ccombstr);
cout << printstr << endl;8. CStringW to CComBSTR
CStringW origw("Hello, World!");
CComBSTR ccombstrw(origw);
CW2A printstrw(ccombstrw);
wcout << printstrw << endl;9. CStringA to string
CStringA origa("Hello, World!");
string basicstring(origa);10. CStringW to wstring
CStringW origw("Hello, World!");
wstring basicstringw(origw);11. CStringA to System::String
CStringA origa("Hello, World!");
String ^systemstring = gcnew String(origa);
delete systemstring;12. CStringA to System::String
CStringW origw("Hello, World!");
String ^systemstringw = gcnew String(origw);
delete systemstringw;从 basic_string 转换
1. string to char *
string orig("Hello, World!");
const size_t newsize = (strlen(orig.c_str()) + 1)*2;
char *nstring = new char[newsize];
strcpy_s(nstring, newsize, orig.c_str());2. string to wchar_t *
string orig("Hello, World!");
const size_t newsizew = strlen(orig.c_str()) + 1;
size_t convertedChars = 0;
wchar_t *wcstring = new wchar_t[newsizew];
mbstowcs_s(&convertedChars, wcstring, newsizew, orig.c_str(), _TRUNCATE);3. wstring to wchar_t *
wstring origw(L"Hello, World!");
wchar_t *wcstring = origw.c_str();4. string to _bstr_t
string orig("Hello, World!");
_bstr_t bstrt(orig.c_str());5. string to CComBSTR
string orig("Hello, World!");
CComBSTR ccombstr(orig.c_str());
CW2A printstr(ccombstr);
cout << printstr << endl;6. string to CStringA
string orig("Hello, World!");
CStringA cstring(orig.c_str());7. string to CStringW
string orig("Hello, World!");
CStringW cstringw(orig.c_str());8. string to System::String
string orig("Hello, World!");
String ^systemstring = gcnew String(orig.c_str());
delete systemstring;参考文档
C++ 在各种字符串类型之间相互转换
https://mxy493.xyz/2021030220973/