Gavilan

CSIS054: Perl Programming

Homework set 3

 
1. Save the file dna.txt. Write a script that will count the number of occurences of each of the letters 'A', 'G', 'T', and 'C'. Report how many times each letter occurs in the file.
2. Your boss at the genetics lab is preparing to order a half-million dollars worth of chemicals based on your analysis of the file above. Convince her, beyond a shadow of a doubt, that your numbers are correct.

3. Save the file words.txt. Write a script that prints each word that occured in the file, one per line, in alphabetical order. If a word occurs in words.txt more than once, only report it once.

(A word is a sequence of 1 or more alphabetical characters and the hyphen character. Words are separated by white-space and/or punctuation. Do not include punctuation, except for hyphenated words, in your report.)

4. The Fibonacci sequence is a series of numbers where the next number is the sum of the previous two. For example, the first 10 numbers are:

1, 1, 2, 3, 5, 8, 13, 21, 34, 55 ...

Write a script that prints out the first 100 Fibonacci numbers.

5. Modify the script from #4 so that after each number, in parentheses, it prints the ratio of that number and the number before it.

For example the 6th line of your output would be:
8     (1.6000)

(Because 8/5 = 1.6000)

6. Modify accounts.pl so that it reads ID numbers and descriptions from a text file. (Instead of from arrays within the script, as it currently does.)

7. Modify your work from #6 so that the data file stores an amount for "Quantity in Stock". Every time the program is run, and a certain item gets sold, have it:

  • check that quantity is above 0
  • re-write the data file to reflect the fact that the item has been sold and now there is 1 less in stock.

 

 

 

 


Address of this page is http://hhh.gavilan.edu/phowell/csis054/03problems.html
Please contact Peter Howell at phowell@gavilan.edu for questions or comments.
Last updated January 16, 2010.