Programming with Mixed Languages Overview

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 following 32-bit languages: Intel® Fortran and Intel® C++.

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, C++, and assembly language. It is organized into the following topics:

• Calling Subprograms from the Main Program
• Summary of Mixed-Language Issues
• Adjusting Calling Conventions in Mixed-Language Programming
• Adjusting Naming Conventions in Mixed-Language Programming
• Prototyping a Procedure in Fortran
• Exchanging and Accessing Data in Mixed-Language Programming
• Handling Data Types in Mixed-Language Programming
• Intel Fortran/C Mixed-Language Programs

For information on converting mixed-language projects, see:

How to Convert Mixed Language Projects