Programming with Mixed Languages

Mixed-language programming is the process of building programs in which the source code is written in two or more languages. It is frequently worthwhile because it lets you:

• Call existing code that is written in another language
• Use procedures that may be difficult to implement in a particular language
• Gain advantages in processing speeds

Mixed-language programming is possible among the 32-bit languages Visual Fortran, Visual C/C++, Visual Basic, and MASM. Mixed-language programming in Win32 is different from that in 16-bit environments, but in many respects it is easier.

Mixed-language programming is the process of establishing rules for naming variables and procedures, for stack use, and for argument passing among routines written in different languages. These rules, as a whole, are the calling convention.

A calling convention includes:

• Stack considerations
  • Does a routine receive a varying or fixed number of arguments?
  • Which routine clears the stack after a call?
    
    
• Naming conventions
  • Is lowercase or uppercase significant or not significant?
  • Are names decorated (as in Visual C++)?
    
    
• Argument passing protocol
  • Are arguments passed by value or by reference?
  • What are the equivalent data types and data structures among languages?

This section gives you the information you need to establish a calling convention among routines written in Fortran, C, Visual C++, Visual Basic, and assembly language. It is organized into the following topics:

• Overview of Mixed-Language Issues
• Exchanging and Accessing Data in Mixed-Language Programming
• Handling Data Types in Mixed-Language Programming
• Visual Fortran/Visual C++ Mixed-Language Programs
• Fortran/Visual Basic Mixed-Language Programs
• Fortran/MASM Mixed-Language Programs