1. Makefiles and Notes on Programming Assignment PA2
Professor Hugh C. Lauer CS-2303, System Programming Concepts
(Slides include materials from The C Programming Language, 2nd edition, by Kernighan and Ritchie, Absolute C++, by Walter Savitch, The C++ Programming Language, Special Edition, by Bjarne Stroustrup, and from C: How to Program, 5th and 6th editions, by Deitel and Deitel)
CS-2303, A-Term 2010
Programming Assignment PA #2

2. Programming Assignment PA #2
Game of Life
Read input line to determine size of board, number of generations, etc.
Dynamically allocate memory for three boards of the appropriate size
Initialize one board to initial configuration (in center)
Play up to n generations
After each generation, test for termination — I.e., same as previous or 2nd previous generation
Print final generation
Optional pause and/or print after each generation for debugging purposes
Free dynamically allocated memory!
CS-2303, A-Term 2010
Programming Assignment PA #2

3. Dynamically Allocated Arrays
Each board is a 2D array
Size determined at run-time
gcc feature of dynamic automatic arrays not appropriate for this assignment
Allocate array of pointers to rows
Allocate array(s) for actual rows
CS-2303, A-Term 2010
Programming Assignment PA #2

4. Programming Assignment PA #2
From this point on, every programming assignment at WPI must be accompanied by makefile or equivalent
Unless otherwise specified
Eclipse, Visual Studio, etc. provide own makefile equivalents
Program Organization
See Lab2
Must have
At least one .h file (your interface)
At least two .c files (together your program)
One makefile
Suggested partition
Life.c — main program, read input & initialize
Game.c — playing game, testing termination
Board.c — utility functions for printing boards, comparison, etc.
Life.h — interface with function headers, extern variable for any globals, etc.
You may choose your own partition of the problem
CS-2303, A-Term 2010
Programming Assignment PA #2

5. Programming Assignment PA #2
Makefile
A scripting “language” that specifies how an application is to be built
Flags, compiler switches, libraries to link
Creates final target and all intermediate files
Recompiles only what needs to be
E.g., source files that have changed
Dependencies upon other files
For PA2, target is the program Life
CS-2303, A-Term 2010
Programming Assignment PA #2

6. Programming Assignment PA #2
Format of Makefile
List of targets
Followed by colon and dependencies
For each target, command line(s) for building target
If any
List of environment variables
For passing switches to commands, etc.
CS-2303, A-Term 2010
Programming Assignment PA #2

7. Programming Assignment PA #2
make command
make
Builds the first target in file makefile
make –f myMakefile
Builds the first target in file myMakefile
make Life
Builds target Life in file makefile
make CFLAGS=-g
Builds first target using compiler flag –g
make CFLAGS=-O2 Life
Builds target Life using compiler flag –O2 (i.e., optimized code)
CS-2303, A-Term 2010
Programming Assignment PA #2

8. Programming Assignment PA #2
Example Makefile
Environment variable (note '=‘ sign)
CFLAGS = -g all: Board.o Game.o Life.o Input.o gcc $(CFLAGS) Board.o Game.o Life.o Input.o -o Life *.o: *.c gcc -Wall -c $(CFLAGS) *.c clean: rm -f *.o Life echo "Make clean completed." Board.o: Life.h Game.o: Life.h
Target (note colon; note also dependencies following colon )
Command lines must be preceded by tabs, not spaces
Command line to build target all
Generic target and command for all .o files Note dependency on corresponding .c file
Very important target — cleans
up the directory (note two commands)
Targets with no commands, only dependencies
CS-2303, A-Term 2010
Programming Assignment PA #2

9. Summary – make & makefiles
make — a useful tool for building all but the most trivial programs
Avoids stupid mistakes in compile commands
Builds only the parts of an application that need to be rebuilt
Can be combined to make very elaborate build “scripts”
CS-2303, A-Term 2010
Programming Assignment PA #2

10. Programming Assignment PA #2
Questions?
Next Topic
CS-2303, A-Term 2010
Programming Assignment PA #2