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

  • Learn How A Global Entertainment Company Saw a 448% ROI Every business today uses software to manage systems, deliver products, and empower employees to do their jobs. But software inevitably breaks, and when it does, businesses lose money -- in the form of dissatisfied customers, missed SLAs or lost productivity. PagerDuty, an operations performance platform, solves this problem by helping operations engineers and developers more effectively manage and resolve incidents across a company's global operations. …

  • Live Event Date: December 18, 2014 @ 2:00 p.m. ET / 11:00 a.m. PT The Internet of Things (IoT) incorporates physical devices into business processes using predictive analytics. While it relies heavily on existing Internet technologies, it differs by including physical devices, specialized protocols, physical analytics, and a unique partner network. To capture the real business value of IoT, the industry must move beyond customized projects to general patterns and platforms. Check out this upcoming webcast …

Most Popular Programming Stories

More for Developers

RSS Feeds