Andrew T. Duchowski--CPSC 241

CPSC 241 Computer Science IV
(Data Structures and Algorithms)
Fall 1998
TTh 12:30--1:45 Daniel 408

Supplement: Makefiles

Sample Makefile
(example Makefile for Assignment 4)

How it works:

The Makefile should exist in the same (seperate) directory (asg4 for instance) as the files that need to be compiled and linked to generate the final executable program.
The files that make up a particular project are modules which contain specific, ``stand-alone'' conceptual information.
The Makefile's job is to check whether any changes have been made to source code files, and then to compile each file seperately (generating object files) before finally assembling (linking) the entire collection of object files into one executable program.
Since there maybe many modules, once all the relevant information is entered into the Makefile, to compile each seperately all you need to do is type ``make''. Here is what you should expect to see: CC -c -I. -I/usr/include/ -I/usr/include/CC/ -o timer.o timer.c CC -c -I. -I/usr/include/ -I/usr/include/CC/ -o arr.o arr.c CC asg4.c timer.o arr.o -o asg4 CC test.c timer.o arr.o -o test You can see above that the Makefile first seperately compiled the modules timer.c, then arr.c, then linked timer.o, arr.o, and asg4.c into the executable asg4. The Makefile then re-used timer.o and arr.o to compile and link with test.c to generate the executable test.

In this particular example of the Makefile, the Makefile expects the following files in the same directory:

Filename	Contents
`arr.h`	`Array` class interface (that is, just the class definition)
`arr.c`	`Array` class implementation (that is, just the code for the class member functions)---needs to `#include "arr.h"` at top
`timer.h`	`Timer` class interface
`timer.c`	`Timer` class implementation---needs to `#include "timer.h"` at top
`test.c`	Tester program to test array class (that is, just the `main()` routine to use and ``exercise'' the array class.
`asg4.c`	Assignment 4 program to test solution

Note that the test.c and asg4.c programs need to #include "arr.h" and asg4.c needs to also #include "timer.h".

Note in the paragraph above which files need to #include files, and, in general, which files need which other files to function properly. This ``need'' is referred to as a dependency. For example, the program file asg4.c uses, or depends on, the information in arr.h and timer.h, and (indirectly) also on the information in arr.c and arr.c. These, in turn, also depend on arr.h and timer.h. This is shown in the graphic below. The Makefile is used to express these dependencies, and it uses this information to manage the compilation and linking of all these related files to generate the final executable programs.