COMP9044 - Week 09 - Laboratory Exercises - Solved

Before the lab you should re-read the relevant lecture slides and their accompanying examples.

 

 

Create a new directory for this lab called lab09, change to this directory, and fetch the provided code for this week by running these commands:

$ mkdir lab09 

$ cd lab09 

$ 2041 fetch lab09 
Or, if you're not working on CSE, you can download the provided code as a zip file or a tar file.

 

 

A Makefile is a useful tool for documenting dependencies among components, as well as ensuring that executable components are up-to-date relative to their source code.

While in general automatically extract all dependencies for complex software systems, a tool that generate most of a Makefile can be very useful.

Your task in this exercise is to write a Perl script makemake.pl which generates an appropriate Makefile for a multi-file C program.

This will require making a number of assumptions.

Your task
Write a Perl script makemake.pl to generate a Makefile that will build the C program whose source code is in the current directory.

The script takes no arguments, and writes the Makefile text to its standard output.

Assumptions
 The current directory contains all code files from only one C program.

The C program is composed only of .c and .h files.

Exactly one .c file will contain a main() function.

The main() function appears on a line that matches the regexp

/^\s*(int|void)\s*main\s*\(/
No other line in the files matches this regex.

 The executable is named after the file containing the main() function (without the .c)

Any line starting with #include is a genuine include line  

(ignore multi-line comments and other preprocessor commands like #if)

  All the dependencies that need to be included in the Makefile involve files that exist in the current directory

Example Output
Three example C programs are available as a zip file

Here is the output your program should produce for each of these examples:


 

$ unzip /web/cs2041/20T2/activities/makemake/examples.zip Archive:  examples.zip    creating: easy/  extracting: easy/graphics.h   inflating: easy/graphics.c .... 

$ cd easy $ ls easymain.c  graphics.c  graphics.h  world.c  world.h 

$ ../makemake.pl >Makefile 

$ cat Makefile 



CC = gcc 

CFLAGS = -Wall -g 

easymain:   easymain.o graphics.o world.o 

    $(CC) $(CFLAGS) -o $@ easymain.o graphics.o world.o 

graphics.o: graphics.h world.h graphics.c easymain.o: world.h graphics.h easymain.c world.o:    world.h world.c 

$ make gcc -Wall -g   -c -o easymain.o easymain.c gcc -Wall -g   -c -o graphics.o graphics.c gcc -Wall -g   -c -o world.o world.c gcc  -o easymain easymain.o graphics.o world.o 

$ cd ../medium 

$ ls 

a.c  a.h  aaa.c  aaa.h  b.c  b.h  bb.c  bb.h  c.c  c.h  common.h  main.c 

$ ../makemake.pl >Makefile 

$ cat Makefile 



CC = gcc 

CFLAGS = -Wall -g 

main:   a.o aaa.o b.o bb.o c.o main.o 

    $(CC) $(CFLAGS) -o $@ a.o aaa.o b.o bb.o c.o main.o 

b.o:    b.h bb.h aaa.h b.c 

c.o:    c.h c.c 

a.o:    common.h a.h a.c bb.o:   bb.h aaa.h bb.c main.o: a.h c.h b.h bb.h aaa.h main.c 

$ make gcc -Wall -g   -c -o a.o a.c gcc -Wall -g   -c -o aaa.o aaa.c gcc -Wall -g   -c -o b.o b.c gcc -Wall -g   -c -o bb.o bb.c gcc -Wall -g   -c -o c.o c.c gcc -Wall -g   -c -o main.o main.c gcc  -o main a.o aaa.o b.o bb.o c.o main.o

$ cd ../hard 

$ ls circ1.c  circ1.h  circ2.c  circ2.h  circmain.c 

$ ../makemake.pl >Makefile 

$ cat Makefile 

 

CC = gcc 

CFLAGS = -Wall -g 

circmain:   circ1.o circ2.o circmain.o 

    $(CC) $(CFLAGS) -o $@ circ1.o circ2.o circmain.o 

circ1.o:    circ1.h circ2.h circ1.c circmain.o: circ1.h circ2.h circmain.c circ2.o:    circ2.h circ1.h circ2.c

$ make gcc -Wall -g   -c -o circ1.o circ1.c 
gcc -Wall -g   -c -o circ2.o circ2.c gcc -Wall -g   -c -o circmain.o circmain.c gcc  -o circmain circ1.o circ2.o circmain.o 
Further Requirements
  You should include four standard lines at the front of every Makefile

# Makefile generated at timestamp in format given above 

CC = gcc 

CFLAGS = -Wall -g 
  There should be a blank line immediately before each Make rule

Hints
 You could use a hash to represent all dependencies

The Perl expression `date` will generate a suitable timestamp

The Perl builtin glob is an easy way to get a list of the .c or .h files in the current directory

You do not need to produce rules for dependencies on standard .h files (e.g. stdio.h) You can assumes includes of standard libraries use <...> notation, e.g:

#include $lt;stdio.h>


Write a Perl regex which matches unary number iff it is composite (not prime).

In other words write a regex that matches a string of n ones iff n is composite.

A test program is provide to assist you in doing this:

 

Download test_regex_prime.pl, or copy it to your CSE account using the following command:

$ cp -n /web/cs2041/20T2/activities/regex_prime/test_regex_prime.pl . 
For example to test the regex ^1(11)+1$ against the integers 2 to 12, you can run

$ chmod 755 test_regex_prime.pl 

$ test_regex_prime.pl 2 12 '^1(11)+1$' 

2 = 11 unary - prime 3 = 111 unary - prime

4    = 1111 unary - composite 

5    = 11111 unary - prime 

6    = 111111 unary - composite

7    = 1111111 unary - prime 

8    = 11111111 unary - composite 

9    = 111111111 unary - prime 

10  = 1111111111 unary - composite 

11  = 11111111111 unary - prime 

12  = 111111111111 unary - composite
Put your solution in regex_prime.txt, for example:

$ test_regex_prime.pl 40 50 "$(cat regex_prime.txt)" 

40  = 1111111111111111111111111111111111111111 unary - composite

41  = 11111111111111111111111111111111111111111 unary - prime 

42  = 111111111111111111111111111111111111111111 unary - composite 

43  = 1111111111111111111111111111111111111111111 unary - prime 

44  = 11111111111111111111111111111111111111111111 unary - composite 

45  = 111111111111111111111111111111111111111111111 unary - composite 

46  = 1111111111111111111111111111111111111111111111 unary - composite 

47  = 11111111111111111111111111111111111111111111111 unary - prime 

48  = 111111111111111111111111111111111111111111111111 unary - composite 

49  = 1111111111111111111111111111111111111111111111111 unary - composite 

50  = 11111111111111111111111111111111111111111111111111 unary - composite 
Your regex must be less than 80 characters.

Hint: you can't do this with a true regular expression, i.e using |*() alone, you need to use features that Perl adds.

Don't google for other people solutions - see if you can come up with your own.