This is directly taken and copied from MSDN but I always end up searching for this. So for my personal and future reference here it is.
Someone on Stackoverflow call this holy grail of string conversion articles.
This topic demonstrates how to convert various Visual C++ string types into other strings. The strings types that are covered include char *, wchar_t*, _bstr_t, CComBSTR, CString, basic_string, and System.String. In all cases, a copy of the string is made when converted to the new type. Any changes made to the new string will not affect the original string, and vice versa.
Converting from char *
Example
This example demonstrates how to convert from a char * to the other string types listed above.
// 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;
}
Output
Hello, World! (char *)
Hello, World! (wchar_t *)
Hello, World! (_bstr_t)
Hello, World! (CComBSTR)
Hello, World! (CString)
Hello, World! (basic_string)
Hello, World! (System::String)
Converting from wchar_t *
Example
This example demonstrates how to convert from a wchar_t * to the other string types listed above.
// 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;
}
Output
Hello, World! (wchar_t *)
Hello, World! (char *)
Hello, World! (_bstr_t)
Hello, World! (CComBSTR)
Hello, World! (CString)
Hello, World! (basic_string)
Hello, World! (System::String)
Converting from _bstr_t
Example
This example demonstrates how to convert from a _bstr_t to the other string types listed above.
// 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;
}
Output
Hello, World! (_bstr_t)
Hello, World! (char *)
Hello, World! (wchar_t *)
Hello, World! (CComBSTR)
Hello, World! (CString)
Hello, World! (basic_string)
Hello, World! (System::String)
Converting from CComBSTR
Example
This example demonstrates how to convert from a CComBSTR to the other string types listed above.
// 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;
}
Output
Hello, World! (CComBSTR)
Hello, World! (char *)
Hello, World! (wchar_t *)
Hello, World! (_bstr_t)
Hello, World! (CString)
Hello, World! (basic_string)
Hello, World! (System::String)
Converting from CString
Example
This example demonstrates how to convert from a CString to the other string types listed above.
// 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;
}
Output
Hello, World! (CString)
Hello, World! (char *)
Hello, World! (wchar_t *)
Hello, World! (_bstr_t)
Hello, World! (CComBSTR)
Hello, World! (basic_string)
Hello, World! (System::String)
Converting from basic_string
Example
This example demonstrates how to convert from a basic_string to the other string types listed above.
// 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;
}
Output
Hello, World! (basic_string)
Hello, World! (char *)
Hello, World! (wchar_t *)
Hello, World! (_bstr_t)
Hello, World! (CComBSTR)
Hello, World! (CString)
Hello, World! (System::String)
Converting from System::String
Example
This example demonstrates how to convert from a System.String to the other string types listed above.
// 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;
}
Output
Hello, World! (System::String)
Hello, World! (char *)
Hello, World! (wchar_t *)
Hello, World! (_bstr_t)
Hello, World! (CComBSTR)
Hello, World! (CString)
Hello, World! (basic_string)