Homework 2, Arguing with the Arguments.

Short Description:

Goals

• Parsed command line arguments.
• Used argv[0] to determine program operation.

Formal Description

For reasons to be specified later write a c++ program called hw2.cpp (executable hw2). Make this program behave differently based on

1. The command line arguments.
2. The name used to invoke the program.

• --arg n:
  • If n is a valid argument number, add this argument to the list to print.
  • If n is invalid print (but an integer)"Invalid argument count " followed by the value of n.
  • If there is no argument for n print " "Usage: --arg n"
  • You may assume that if n is given it is an integer and can be converted using stoi.
  • This argument may be given multiple times.
    • hw2 --arg 1 --arg 2 --arg 4 --arg 2 should print --arg, 1, --arg, 1. (But see the spec)
  • Only print this after all arguments have been parsed.
    • Print "The selected args are:"
    • Print the selected arguments in the order given in the command line. (I used a vector of ints)
    • Print an endline.
• --args or -a:
  • By default this option is off.
  • Print the header "The args are:"
  • Print all of the command line arguments as specified below
  • Print an endline.
• --var varname
  • If varname is an environment variable name, add the corresponding var=value pair to the list.
  • If varname is not supplied, print the error "Usage: --env varname."
  • This can be ignored if there is no corresponding varname in the environment.
  • This argument may be given multiple times.
  • Only print this after all arguments have been parsed.
• --env or -e:
  • By default this option is off.
  • Print the header "The the environment is:"
  • Print all of the command line arguments as specified below
  • Print an endline.

The output format should be each line starts with a tab, then the next value to print.

• Special arguments requested
• All arguments, if requested.
• Special environment variables if requested
• All environment variables if requested.
• A blank line.

[bennett@mirkwood closed]$ hw2 --arg 0 --var HOME -a
The selected args are:
        hw2

The args are:
        --arg
        0
        --var
        HOME
        -a

The selected environment is:
        HOME=/home/bennett

Your program should examine argv[0] and determine how it should execute.

• hw5 should display nothing by default.
• myarg should display the arguments by default (-a, --args)
• myenv should display the environment by default (-e --env)

Notes

• You may parse the command line arguments any way you wish.
• You may use all of the standard library. I used vectors and find.
• You may write this in c if you wish.

Extra Credit

• Search the environment for the variable MY_ARGS_ARGS which should contain a string of comma separated numbers. Use these for -arg
• Search the environment for the variable MY_ARGS_ENV which should contain a string of comma separated variable names. Use these for -env

• [bennett@mirkwood closed]$ export MY_ARGS_ARGS=3,2,4,1,5
  [bennett@mirkwood closed]$ hw2 --var MY_ARGS_ARGS
  The selected environment is:
          MY_ARGS_ARGS=3,2,4,1,5
  [bennett@mirkwood closed]$ echo $MY_ARGS_ARGS
  3,2,4,1,5 

• Write this in python. Note, you must provide a c/c++ version.
• Write this in bash. Note, you must provide a c/c++ version.

Required Files

Submission