Converting Between MFC/C++ and .NET Types

Welcome to this week's installment of .NET Tips & Techniques! Each week, award-winning Architect and Lead Programmer Tom Archer from the Archer Consulting Group demonstrates how to perform a practical .NET programming task using either C# or Managed C++ Extensions.

Many .NET methods are very picky about the types that you can pass as parameters. For example, the sockets, cryptography, and several of the streaming methods require byte arrays, which you must first convert from CString objects or C++ types. In addition, despite the fact that IJW alleviates many conversion issues, several situations still require you to manually convert a .NET type to a C++ type. As a result, converting between types is frequently a sticking point for coders new to mixing MFC and .NET.

This article illustrates some basic conversion code that should help you if you find yourself about to throw your monitor against the wall after the latest "can't convert x to y" compiler error message!

Converting CString objects to a .NET Byte array

CString str = _T("CString to be converted to a byte array");
Byte barr[] = new Byte[str.GetLength()];
for(int i   = 0; i < str.GetLength(); i++)
   barr[i]  = static_cast<Byte>(str [i]);

Converting String objects to a C++ char array

#include <vcclr.h>    // Needed for the PtrToStringChars function
//...
String* s = S"String to be converted to a char array";
const __wchar_t __pin * str = PtrToStringChars(s);

Converting String objects to a .NET Byte array

String* str = S"String to be converted to a byte array";
Byte barr[] = new Byte[str->Length];
for(int i=0; i<str->Length; i++)
   barr[i] = static_cast<Byte>(str->ToCharArray()[i]);

Converting Int32 objects to a managed char array

Int32 myInt = 42;
unsigned char myArray __gc[] = BitConverter::GetBytes(myInt);

Got More?

This is by no means meant to be a complete compilation of all conversions between MFC/C++ and .NET. However, it will handle the majority of the cases you face. If you would like to add a conversion, just drop me a line. If I add it to the article, I'll, of course, give you credit for the input.



About the Author

Tom Archer - MSFT

I am a Program Manager and Content Strategist for the Microsoft MSDN Online team managing the Windows Vista and Visual C++ developer centers. Before being employed at Microsoft, I was awarded MVP status for the Visual C++ product. A 20+ year veteran of programming with various languages - C++, C, Assembler, RPG III/400, PL/I, etc. - I've also written many technical books (Inside C#, Extending MFC Applications with the .NET Framework, Visual C++.NET Bible, etc.) and 100+ online articles.

Comments

  • There are no comments yet. Be the first to comment!

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • On-demand Event Event Date: February 12, 2015 The evolution of systems engineering with the SysML modeling language has resulted in improved requirements specification, better architectural definition, and better hand-off to downstream engineering. Agile methods have proven successful in the software domain, but how can these methods be applied to systems engineering? Check out this webcast and join Bruce Powel Douglass, author of Real-Time Agility, as he discusses how agile methods have had a tremendous …

  • The mobile market is white hot. Building a well-crafted product development plan that addresses market research, strategy, design, and development will provide the greatest chance for success. Each phase of an app's lifecycle is critical to the its overall success and feeds into the next step of the process of product development for the app. This white paper examines the five key phases of mobile app creation, one by one, to understand how they work together to help create a successful mobile app.

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date