Shell Programming and Scripting

You are correct, the amount of coins....37 = 1 quarter, 1 dime and 2 pennies

The first one is correct

.. well, that's a heck of an assignment to get you to "get used to scripting". In any case..

I don't know what's in this file "mynum" that you are grepping from, but, for this particular situation I see 2 approaches here:
1.- The newbie
2.- The mathematician.

The newbie is simple: 100 cents is a small finite number, and having 4 types of coins to work with (pennies, nickels, dimes, quaters) further reduces the permutations. So, you can basically create a file with 100 lines that describe each possible combination of coins depending on the input:

Code:

# cat myfile
1 one penny
2 two pennies
...
13 one dime 3 pennies
...
37 one quarter one dime 2 pennies
...

Here what you would do, when the user inputs the amount, you'd grep myfile for that number and match it to a line in myfile that starts with that number, then output the rest of the line.

The mathematician, well, that one can get complicated. For that, you basically need to declare variables for each type of coin, then match the variables to the user input. There are probably 1000 ways to parse this: one approach would be to match the highest variable to the user input, once user input is less than variable, you'd add it to a numeric variable, then you go to the next highest variable, and so on. Something like:

Code:

Qcount=0
Qtotal=0
Dcount=0
Dtotal=0
Ncount=0
Ntotal=0
Pcount=0
Ptotal=0
TOTAL=$USERINPUT

# Find number of quarters
while  (( ${TOTAL} >= 25 })); do
               let Qcount=${Qcount}+1
               let Qtotal=${Qtotal}+25
               let TOTAL=${TOTAL}-25
done

Once TOTAL is less than Qtotal, Qcount will tell you how many quarters are in the original TOTAL, and TOTAL what is left, which should be less than 25 cents.
Then you'd use the same loop to figure out the dimes, then the nickels, then the pennies.
When you are finished, you can echo Qcount, Dcount, etc...

The loop will act something like this:

Code:

while 87 is bigger than or equal to 25, do
          let Qcount=1
          let Qtotal=25
          let TOTAL=62
   do it again
while 62 is bigger than or equal to 25, do
            let Qcount=2
            let Qtotal=50
            let TOTAL=37
   do it again
while 37 is bigger than or equal to 25, do

... and so on.

Get the idea?

Like I said, there are probably 1000 ways to work this, and I haven't tested the loops, but that should give you a start.

Thanks for the reply "system", I will give it a shot.

If you are just learning shell scripting, learn to write scripts that will run in any POSIX shell (which includes Korn shell).

This is a relatively trivial exercise; it took me a couple of minutes and about a dozen lines of code.

A more interesting exercise would be to do it without a single-unit coin (but with other odd-denomination coins).