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 allows you to:

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, and in many respects it is easier.

To properly create mixed-language programs, rules must be established 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 external names altered?
Argument passing protocol
- Are arguments passed by value or by reference?
- What are the equivalent data types and data structures among languages?

This section provides information on the calling conventions available when writing routines written in Fortran, C, Visual C++, Visual Basic, and ia32 assembly language. It is organized into the following topics: