C CLI Converting from System String to std string

Question

Can someone please post a simple code that would convert   System  String    To   C   std  string  I e   I just want to assign the value of   String  originalString    To   std  string newString

User · Answer

Here are some conversion routines I wrote many years ago for a c   cli project  they should still work    void StringToStlWString   System  String const  s  std  wstring amp  os                String  string   const cast lt String  gt  s           const wchar t  chars   reinterpret cast lt const wchar t  gt   Marshal  StringToHGlobalUni string   ToPointer             os   chars          Marshal  FreeHGlobal IntPtr  void  chars               System  String  StlWStringToString  std  wstring const amp  os            String  str   gcnew String os c str               String  str   gcnew String              return str             System  String  WPtrToString wchar t const  pData  int length            if  length    0                  use null termination             length   wcslen pData               if  length    0                    System  String  ret                       return ret                                   System  IntPtr bfr   System  IntPtr const cast lt wchar t  gt  pData            System  String  ret   System  Runtime  InteropServices  Marshal  PtrToStringUni bfr  length           return ret             void Utf8ToStlWString char const  pUtfString  std  wstring amp  stlString              wchar t  pString          MAKE WIDEPTR FROMUTF8 pString  pUtfString           stlString   pString             void Utf8ToStlWStringN char const  pUtfString  std  wstring amp  stlString  ULONG length              wchar t  pString          MAKE WIDEPTR FROMUTF8N pString  pUtfString  length           stlString   pString

User · Answer

Check out System  Runtime  InteropServices  Marshal  StringToCoTaskMemUni   and its friends   Sorry can t post code now  I don t have VS on this machine to check it compiles before posting

User · Answer

This worked for me    include  lt stdlib h gt   include  lt string h gt   include  lt msclr marshal cppstd h gt       using namespace msclr  interop       System  String  clrString    TextoDeBoton   std  string stdString   marshal as lt std  string gt  clrString     String  to std   System  String  myString   marshal as lt System  String  gt  MyBasicStirng     std to String  prueba CopyInfo stdString     MyMethod        Where  String    TextoDeBoton    and stdString is a  normal  string

User · Answer

You can easily do this as follows   include  lt msclr marshal cppstd h gt   System  String  xyz  Hi boys     std  string converted xyz msclr  interop  marshal as lt  std  string  gt   xyz

User · Answer

I spent hours trying to convert a windows form listbox ToString value to a standard string so that I could use it with fstream to output to a txt file  My Visual Studio didn t come with marshal header files which several answers I found said to use  After so much trial and error I finally found a solution to the problem that just uses System  Runtime  InteropServices   void MarshalString   String   s  string amp  os        using namespace Runtime  InteropServices     const char  chars           const char   Marshal  StringToHGlobalAnsi s   ToPointer       os   chars     Marshal  FreeHGlobal IntPtr  void  chars         this is the code to use the function  scheduleBox- gt SetSelected 0 true   string a    test   String   c   gcnew String scheduleBox- gt SelectedItem- gt ToString     MarshalString c  a   filestream  lt  lt  a    And here is the MSDN page with the example  http   msdn microsoft com en-us library 1b4az623 v vs 80  aspx  I know it s a pretty simple solution but this took me HOURS of troubleshooting and visiting several forums to finally find something that worked

User · Answer

C  uses the UTF16 format for its strings  So  besides just converting the types  you should also be conscious about the string s actual format   When compiling for Multi-byte Character set Visual Studio and the Win API assumes UTF8  Actually windows encoding which is Windows-28591    When compiling for Unicode Character set Visual studio and the Win API assume UTF16   So  you must convert the string from UTF16 to UTF8 format as well  and not just convert to std  string  This will become necessary when working with multi-character formats like some non-latin languages   The idea is to decide that std  wstring always represents UTF16  And std  string always represents UTF8    This isn t enforced by the compiler  it s more of a good policy to have     include  stdafx h   include  lt string gt   include  lt codecvt gt   include  lt msclr marshal cppstd h gt   using namespace System   int main array lt System  String   gt   args        System  String  managedString    test        msclr  interop  marshal context context         Actual format is UTF16  so represent as wstring     std  wstring utf16NativeString   context marshal as lt std  wstring gt  managedString           C  11 format converter     std  wstring convert lt std  codecvt utf8 utf16 lt wchar t gt  gt  convert         convert to UTF8 and std  string     std  string utf8NativeString   convert to bytes utf16NativeString        return 0      Or have it in a more compact syntax   int main array lt System  String   gt   args        System  String  managedString    test        msclr  interop  marshal context context      std  wstring convert lt std  codecvt utf8 utf16 lt wchar t gt  gt  convert       std  string utf8NativeString   convert to bytes context marshal as lt std  wstring gt  managedString         return 0

User · Answer

Don t roll your own  use these handy  and extensible  wrappers provided by Microsoft   For example    include  lt msclr marshal cppstd h gt   System  String  managed    test   std  string unmanaged   msclr  interop  marshal as lt std  string gt  managed

User · Answer

I used VS2012 to write below code-- convert system string to Standard Sting           include  stdafx h           include  lt iostream gt           include  lt string gt            using namespace System          using namespace Runtime  InteropServices             void MarshalString   String  s  std  string amp  outputstring                          const char  kPtoC     const char    Marshal  StringToHGlobalAnsi s   ToPointer                                                                       outputstring   kPtoC               Marshal  FreeHGlobal IntPtr  void  kPtoC                            int  tmain int argc   TCHAR  argv                           std  string strNativeString                 String   strManagedString    Temp                 MarshalString strManagedString  strNativeString                  std  cout  lt  lt  strNativeString  lt  lt  std  endl                 return 0

User · Answer

I like to stay away from the marshaller   Using CString newString originalString     Seems much cleaner and faster to me  No need to worry about creating and deleting a context

User · Answer

I found an easy way to get a std  string from a String  is to use sprintf      char cStr 50      0    String  clrString    Hello   if  clrString- gt Length  lt  sizeof cStr     sprintf cStr    s   clrString   std  string stlString cStr     No need to call the Marshal functions   UPDATE Thanks to Eric  I ve modified the sample code to check for the size of the input string to prevent buffer overflow

[string] C++/CLI Converting from System::String^ to std::string

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