Week 3 Laboratory — Command Line Arguments & Makefiles

We have created some scripts that can automatically run your program against some tests. To run these tests you can execute the dry run program with an argument that corresponds to the lab and week, i.e. lab03 for this week. It expects to find all the programs to be submitted as part of this lab in the current directory. You can use dry run as follows:

prompt$ ~cs1921/bin/dryrun lab03

or specific tests (e.g. test #2) as follows:

prompt$ ~cs1921/bin/dryrun lab03 2

Exercises

1. Write a program called concat.c that outputs, in separate lines,

   • the name of the program
   • the number of command line arguments
   • all arguments from the command line in a single line

   Examples of this program executing are:

   prompt$ ./concat Test1 Test2 Test3 Name of the program: ./concat Number of arguments: 3 Test1Test2Test3

   prompt$ ./concat c o m p 19 21 Name of the program: ./concat Number of arguments: 6 comp1921

   prompt$ ./concat comp1921 Name of the program: ./concat Number of arguments: 1 comp1921

   prompt$ ./concat 1 2 3 4 5 6 7 8 9 Name of the program: ./concat Number of arguments: 9 123456789

   prompt$ ./concat Name of the program: ./concat Number of arguments: 0

   Note: You should

   • match the output exactly (do not change the text in any way)
   • format your program correctly (use parentheses and indentation properly)
   • poor formatting will lead to loss of marks

2. Write a program called add3.c that sums precisely 3 numerical arguments from the command line:

   • Each numerical arg may be positive (e.g. 1), negative (e.g. -1) or floating point (1.0 or -1.0)

     • there should be no more and no less than 3 numerical arguments
     • the sum of the 3 args is printed on stdout, and EXIT_SUCCESS is returned by the program
     • you should use only integers to compute the sum: floating point numbers on the command line will be truncated

   • If there are less than 3 args, or more than 3, then an appropriate error message is output (see the testcases below) on stderr, and the program returns EXIT_FAILURE
   • If one of the 3 args is non-numeric, then an appropriate error message is output (see the testcases below) on stderr, and the program returns EXIT_FAILURE

   Examples of 'usages' that result in correct behaviour are the following:

   prompt$ ./add3 1 2 3 6

   prompt$ ./add3 9678 12505 342198 364381

   prompt$ ./add3 0 0 0 0

   prompt$ ./add3 -1 -2 -3 -6

   prompt$ ./add3 1.0 2.0 3.0 6

   prompt$ ./add3 -1.0 -2.0 3 0

   prompt$ ./add3 1.9 1 1 3

   Examples of usages that generate error messages are the following:

   prompt$ ./add3 ./add3: incorrect number of args

   prompt$ ./add3 1 ./add3: incorrect number of args

   prompt$ ./add3 1 2 ./add3: incorrect number of args

   prompt$ ./add3 1 2 3 4 ./add3: incorrect number of args

   prompt$ ./add3 1 2 a ./add3: found non-numerical arg

3. Write a program called sumnum.c that sums the arguments on the command line and prints the result on stdout. If there are no arguments, the program generates no output.

   • You should use a Makefile in this exercise to build the executable, so the command

     prompt$ make

     should result in the executable sumnum being generated. Examples of this program executing are:

     prompt$ ./sumnum 1 2 3 6

     prompt$ ./sumnum 123 123

     prompt$ ./sumnum

     In the first case above, the user has entered the command ./sumnum 1 2 3. (You may assume that each argument is well-formed: i.e. it is either numeric, or alphabetic.)

   • Make the program robust by generating an error message if one of the arguments is non-numeric. For example,

     prompt$ ./sumnum 1 fred 2 error: argument fred is non-numeric

4. Write a program called countplus.c that prints on stdout a sequence of numbers from 0 to a non-negative number given on the command line. The numbers in the sequence are separated by commas. Examples of the program executing are:

   prompt$ ./countplus 1 0,1

   prompt$ ./countplus 10 0,1,2,3,4,5,6,7,8,9,10

   prompt$ ./countplus 0 0

   You may assume that the argument is a non-negative integer, and the output appears on one line.

   You should extend the previous Makefile to build the executable.
   Make you program more robust by handling the following exceptions: if there are no arguments on the command line, or there is more than 1 argument, then a 'usage' message should be output. For example,

   prompt$ ./countplus Usage: ./countplus number

   prompt$ ./countplus 1 2 Usage: ./countplus number

   The output of your program should match the above exactly.

For this lab, you should submit your files using the following give command (but the command may not work until the lab itself):

  give  cs1921  lab03  concat.c  add3.c  Makefile  sumnum.c  countplus.c

Make sure you spell the filenames correctly. The Makefile should contain rules to build the executables sumnum.c and countplus.c.