Q:

Batch file for parsing command line input that contains comma separated values

I am working on a command line utility that takes set of input parameters as command.
Those input parameters are then validated against predefined names. The utility is invoked in this manner:
runUtility.cmd -A  -B x,y,z  -C w
Here parameters are A, B and C (one that starts with -).
Now the validation rules are as follows:

Parameter's name should match predefined names, so that one can not pass any invalid parameter say -UVW
Parameter may or may not have a value. In above example -A has no value, while -B has x,y,z and -C has w.

I have written this code to validate the inputs:
:validate

set argument=%1
set argumentValue=%2

if "%argument%" == "-A" (   
    shift   
    goto validate
)

if "%argument%" == "-B" (
    if "%argumentValue%" == "" (
        echo Empty value for -B
        goto end
    )
    shift
    shift 
    goto validate       
)

if "%argument%" == "-C" (
    if "%argumentValue%" == "" (
        echo Empty value for -C
        goto end
    )
    shift
    shift  
    goto validate      
)

if %argument%" == "" (
        goto end
)

Argument %argument% is invalid

:end        

But this does not seem to work, as -B has comma separated values, so for B when it does two shifts, in the next iteration,  y becomes %1 and z becomes %2. Since y is not a parameter, it fails with last line of code that "Argument y is invalid".
Actually comma is taken as delimiter by SHIFT command, so x,y,z does remain a single value.
I want x,y,z to be taken as a single value OR is there any other way to process this?
I am bit new to batch scripting , I tried with FOR loop but there I was not able to get %1 and %2 together in every iteration.

A:

Batch uses any combination of space, comma, semicolon, tab, and equal to delimit parameters. If you want to include any of those characters in a parameter, then the parameter must be quoted.
runUtility.cmd -A -B "x,y,z" -C w

Your script can remove the enclosing quotes with the ~ modifier. It is also a good idea to enclose your entire assignment within quotes to guard against problem characters like &, |, etc. The double quotes in the assignment below will not be included in the value.
set "argumentValue=%~2"

I developed an option parser that you might want to look at: Windows Bat file optional argument parsing.
The parsing code hardly changes regardless what options you define. The only things that have to change are the definition of your options using a single variable, the SHIFT /3 should be modified to SHIFT /1, every %~3 becomes %~1, and %~4 becomes %~2.
The option parser has the ability to automatically supply default values for unspecified options.
Assuming you do not have default values, your options would be defined as
set "options=-A: -B:"" -C:"""

Meaning an -A option that does not take a value, and -B and -C options that take values but by default are undefined.
The options are stored in variables that match the option name (dash included).

