How to: Convert System::String to wchar_t* or char*


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The latest version of this topic can be found at How to: Convert System::String to wchar_t* or char*.

You can use PtrToStringChars in Vcclr.h to convert String to native wchar_t * or char *. This always returns a wide Unicode string pointer because CLR strings are internally Unicode. You can then convert from wide as shown in the following example.

// convert_string_to_wchar.cpp  
// compile with: /clr  
#include < stdio.h >  
#include < stdlib.h >  
#include < vcclr.h >  
using namespace System;  
int main() {  
   String ^str = "Hello";  
   // Pin memory so GC can't move it while native function is called  
   pin_ptr<const wchar_t> wch = PtrToStringChars(str);  
   printf_s("%S\n", wch);  
   // Conversion to char* :  
   // Can just convert wchar_t* to char* using one of the   
   // conversion functions such as:   
   // WideCharToMultiByte()  
   // wcstombs_s()  
   // ... etc  
   size_t convertedChars = 0;  
   size_t  sizeInBytes = ((str->Length + 1) * 2);  
   errno_t err = 0;  
   char    *ch = (char *)malloc(sizeInBytes);  
   err = wcstombs_s(&convertedChars,   
                    ch, sizeInBytes,  
                    wch, sizeInBytes);  
   if (err != 0)  
      printf_s("wcstombs_s  failed!\n");  
    printf_s("%s\n", ch);  


Using C++ Interop (Implicit PInvoke)