For this assignment, you are to:

1.    Modify the output format of your Python script from Assignment 1 to match the input format of your C program from Assignment 2.

2.    Write a program in C to generate random input for your Python script.

3.    Write a driver program in C that, using Inter-Process Communication (IPC), links the output of the random input generator to the input of the Python script, and the output of the Python script to the input of the C program from Assignment 2.

Resource

The online book, \Advanced Linux Programming," will be useful for this assignment and beyond.

Sample Run

You should name the driver's executable a3750T26. In the following, we assume that \$" is the shell command-prompt.

$ make clean

$ make

$ chmod u+x ./a1750T26.py

$ ./a3750T26 -s 5 -n 4 -l 5

V = 8

E = f<0,2>,<0,3>,<0,4>,<1,3>,<4,7>,<5,2>,<5,6>g

s 2 4

2-0-4

In the above, the first four lines make your executable, ensure your Python script is executable, and run the driver program with some command-line arguments. Then, the lines \V = . . . ," \E = . . . ," and \2-0-4" are output. The input the user provided to your program via stdin is \s 2 4."

Input, Output and Error

Your program should take input from stdin, and output to stdout. Errors should be output to stderr. Errors should always start with \Error:" followed by a brief description. All your processes should terminate gracefully (and quietly) once you see EOF at stdin. Your program should not generate any extraneous output; for example, do not print out prompt strings such as \please enter input" and things like that.

As the example above indicates, there are two kinds of inputs the user provides. One is via the command-line arguments -s and -n. This is done once only, when your program is run. The other is the \s" input at stdin, which may be issued repeatedly, just as in Assignment 2. Your program should output a shortest path.

We will not test your program for format errors in the input. That is, the command-line arguments, if specified, will be formatted correctly, and the s input will also be formatted correctly. Of course, we may omit one or both command-line arguments (see below for what to do in such cases), and specify vertex IDs to s that do not exist, or between whom a path does not exist. The latter two  cases should cause your program to report an error.