如何：在各種字符串類型之間進行轉換（zz）

 

zz from：http://msdn.microsoft.com/zh-cn/library/ms235631(VS.80).aspx

本主題演示如何將各種 Visual C++ 字符串類型轉換爲其他字符串。可以轉換的字符串類型包括 char *、wchar_t*、_bstr_t、CComBSTR、CString、basic_string 和 System.String。在所有情況下，在將字符串轉換爲新類型時，都會創建字符串的副本。對新字符串進行的任何更改都不會影響原始字符串，反之亦然。

 

 

1. 從 char * 轉換

// convert_from_char.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { char *orig = "Hello, World!"; cout << orig << " (char *)" << endl; // Convert to a wchar_t* size_t origsize = strlen(orig) + 1; const size_t newsize = 100; size_t convertedChars = 0; wchar_t wcstring[newsize]; mbstowcs_s(&convertedChars, wcstring, origsize, orig, _TRUNCATE); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string string basicstring(orig); basicstring += " (basic_string)"; cout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }  

 

2. 從 wchar_t * 轉換

// convert_from_wchar_t.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { wchar_t *orig = L"Hello, World!"; wcout << orig << L" (wchar_t *)" << endl; // Convert to a char* size_t origsize = wcslen(orig) + 1; const size_t newsize = 100; size_t convertedChars = 0; char nstring[newsize]; wcstombs_s(&convertedChars, nstring, origsize, orig, _TRUNCATE); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string wstring basicstring(orig); basicstring += L" (basic_string)"; wcout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }  

 

3. 從 _bstr_t 轉換

// convert_from_bstr_t.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { _bstr_t orig("Hello, World!"); wcout << orig << " (_bstr_t)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; strcpy_s(nstring, (char *)orig); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* wchar_t wcstring[newsize]; wcscpy_s(wcstring, (wchar_t *)orig); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a CComBSTR CComBSTR ccombstr((char *)orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring((char *)orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string string basicstring((char *)orig); basicstring += " (basic_string)"; cout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String((char *)orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }  

 

4. 從 CComBSTR 轉換

// convert_from_ccombstr.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" #include "vcclr.h" using namespace std; using namespace System; using namespace System::Runtime::InteropServices; int main() { CComBSTR orig("Hello, World!"); CW2A printstr(orig); cout << printstr << " (CComBSTR)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; CW2A tmpstr1(orig); strcpy_s(nstring, tmpstr1); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* wchar_t wcstring[newsize]; wcscpy_s(wcstring, orig); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CString CString cstring(orig); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string wstring basicstring(orig); basicstring += L" (basic_string)"; wcout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }  

 

5. 從CString轉換

// convert_from_cstring.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { CString orig("Hello, World!"); wcout << orig << " (CString)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; strcpy_s(nstring, orig); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* // You must first convert to a char * for this to work. size_t origsize = strlen(orig) + 1; size_t convertedChars = 0; wchar_t wcstring[newsize]; mbstowcs_s(&convertedChars, wcstring, origsize, orig, _TRUNCATE); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a basic_string string basicstring(orig); basicstring += " (basic_string)"; cout << basicstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }  

 

6. 從 basic_string 轉換

// convert_from_basic_string.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" using namespace std; using namespace System; int main() { string orig("Hello, World!"); cout << orig << " (basic_string)" << endl; // Convert to a char* const size_t newsize = 100; char nstring[newsize]; strcpy_s(nstring, orig.c_str()); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* // You must first convert to a char * for this to work. size_t origsize = strlen(orig.c_str()) + 1; size_t convertedChars = 0; wchar_t wcstring[newsize]; mbstowcs_s(&convertedChars, wcstring, origsize, orig.c_str(), _TRUNCATE); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(orig.c_str()); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(orig.c_str()); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(orig.c_str()); cstring += " (CString)"; cout << cstring << endl; // Convert to a System::String String ^systemstring = gcnew String(orig.c_str()); systemstring += " (System::String)"; Console::WriteLine("{0}", systemstring); delete systemstring; }  

 

7. 從 System::String 轉換

// convert_from_system_string.cpp // compile with: /clr /link comsuppw.lib #include <iostream> #include <stdlib.h> #include <string> #include "atlbase.h" #include "atlstr.h" #include "comutil.h" #include "vcclr.h" using namespace std; using namespace System; using namespace System::Runtime::InteropServices; int main() { String ^orig = gcnew String("Hello, World!"); Console::WriteLine("{0} (System::String)", orig); pin_ptr<const wchar_t> wch = PtrToStringChars(orig); // Convert to a char* size_t origsize = wcslen(wch) + 1; const size_t newsize = 100; size_t convertedChars = 0; char nstring[newsize]; wcstombs_s(&convertedChars, nstring, origsize, wch, _TRUNCATE); strcat_s(nstring, " (char *)"); cout << nstring << endl; // Convert to a wchar_t* wchar_t wcstring[newsize]; wcscpy_s(wcstring, wch); wcscat_s(wcstring, L" (wchar_t *)"); wcout << wcstring << endl; // Convert to a _bstr_t _bstr_t bstrt(wch); bstrt += " (_bstr_t)"; cout << bstrt << endl; // Convert to a CComBSTR CComBSTR ccombstr(wch); if (ccombstr.Append(L" (CComBSTR)") == S_OK) { CW2A printstr(ccombstr); cout << printstr << endl; } // Convert to a CString CString cstring(wch); cstring += " (CString)"; cout << cstring << endl; // Convert to a basic_string wstring basicstring(wch); basicstring += L" (basic_string)"; wcout << basicstring << endl; delete orig; }