Homework 6

If you need more information about the GNU make system, you can find its manual at http://www.gnu.org/software/make/manual/make.html. For instance, you may find the section entitled An Introduction to Makefiles helpful.

1. Rewrite the following make rule to use an automatic variable in the command. (1~pt.)

   file.o: file.cpp
       g++ -c file.cpp

2. Rewrite the same rule as a pattern matching rule that compiles any .cpp file into a .o file. (1~pt.)
3. Rewrite the same rule as a suffix rule that compiles any .cpp file into a .o file. (1~pt.) Note: you can find information about suffix rules in make's manual.

4. Why do pattern matching rules need automatic variables? Why can't they just use a plain filename in their command? (1~pt.)

    

   The files in the current directory are listed below with their timestamps. A higher number means the file is newer.

   Time Stamp	File Name
   2	file.o
   1	file1.cpp
   3	file2.cpp

   If the following make rule is run what are the values of the following variables?

   file.o: file1.cpp file2.cpp
       echo $<
       echo $^
       echo $?

5. $< (1~pt.)
6. $^ (1~pt.)
7. $? (1~pt.)
8. \What does the VPATH variable do? The VPATH was discussed in lecture and is also discussed in make's manual. (1~pt.)
9. If the VPATH variable has multiple directories in it you may not know in what directory a particular file will be found. What is the advantage of automatic variables in this case? (1~pt.)
10. What is an implicit rule? (1~pt.)

Submission

Please create a text file (not MS Word, not PDF, just plain text) for your answers and a PDF file for your drawing for question 5. Place both files in an archive and upload the archive to the moodle.