Writing Larger Programs

This Chapter deals with theoretical and practical aspects that need to be considered when writing larger programs.

When writing large programs we should divide programs up into modules. These would be separate source files. main() would be in one file, main.c say, the others will contain functions.

We can create our own library of functions by writing a suite of subroutines in one (or more) modules. In fact modules can be shared amongst many programs by simply including the modules at compilation as we will see shortly..

There are many advantages to this approach:

• the modules will naturally divide into common groups of functions.
• we can compile each module separately and link in compiled modules (more on this later).
• UNIX utilities such as make help us maintain large systems (see later).

• Header files
• External variables and functions
  • Scope of externals
• The Make Utility
• Make Programming
• Creating a makefile
• Make macros
• Running Make