Spring semester

In two of my programming classes, I will apparently be pair programming and working with the command line interface in a Unix environment. 

 

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Die Rich Craps game in Java

For one of my programming projects last year, our task was to create a version of the Die Rich Craps game. I finally decided to put my code for that project (and others) on Github.

My submitted project looks, in retrospect, a little unreadable but I did try to comment the code appropriately. My Die Rich craps implementation is contains:

  1. 2 while loops
  2. 1 for loop
  3. 4 if/else statements
  4. 2 if statements
  5. 4 if-else-if laddered statements.

So, I am in the process of rewriting it to be a little shorter and slightly more testable. I have a rough & incomplete sketch which goes:

1) Create a Players class which will contain key variables that are unique to each instance of the Players class and a final static class variable which applies to all members of the Players class.

2) Create the DieRich class file (which includes the main method)

That’s as far as I’ve gotten. So far, it’s a good experiment to think about breaking the program/project into tasks and writing code accordingly.

I visited a software product company recently and I learned that tests (regression and unit tests) are exceedingly important & take up just as much time as coding does! The developer I ‘shadowed’ walked me through the process of unit testing which I will try to implement in my projects this semester.

Verifying Input

When creating constructors and adding setters, I’ve been taught to verify all input passed to the method. In working through the ProjectEuler exercises, I’ve made use of helper methods that hadformal parameters but didn’t necessarily verify the input (bad habit). With Problem8, I decided to put this into practice. The problem was: “find the greatest product of five consecutive digits in a 1000-digit number.’ I solved this problem using 2 for loops:

  1. With the first for loop, I created a String object that contained 5 characters at one time. With every iteration of the for loop, the sentinel would be updated by 1 and thus, the String would be updated to contain a new sequence of 5 characters e.g.  startingString.substring(i,i+4).
  2. Rather than perform the required computation in the 1st for loop which would made my program faster, I decided to create a helper method which would accept a String and return the product of all the digits in that String. 
  3. The first iteration of my helper method didn’t include any checks to verify that the String didn’t have any non-word characters which would have caused a NumberFormat exception (I converted the digits in the String object using Integer.parseInt(String name)).
    Java-numberformat

     So, I added some to the helper method I used to make sure that the algorithm would return correct/appropriate output when provided input that fits the formal parameter specifications. 

  4. First, I stripped the String of all non-word characters with this command: digits.replaceAll(“\W”,””); An alternate and informative way to alert the user to the ‘bad’ input is via the try { } catch { } feature of Java.
  5. Another thing to check for is if, after stripping all non-word characters from the String passed to the helper method, the String’s length is 0 i.e. the String is an empty String, I would return 0 as the product of the String in that case instead of the value of Product which was initialized to 1. That was taken care of via a simple conditional statement. Here’s the code for my helper method: 

    https://gist.github.com/1531024

Overall, it’ll be good practice for me to view my code with an eye to splitting off ‘tasks’ into helper methods and making sure that input is verified. 

Happy December break! :)

I’m thankful for family and thankful that my faculties are still sharp. 🙂 Long way of saying my semester ended on a very strong note.

Taking a break from stuffing myself, I thought of a crude solution to Problem 5 from ProjectEuler.net. Caution: With the way I solved the problem, I’ll run into an integer oveflow situation for N > 23. Without further ado, here’s the gist of my rough solution:

https://gist.github.com/1522663

I’ve started using Github (@janoulle) and I know the basics of creating/cloning a repo, adding, committing and pushing. I may have to pony up for a private repo for placing my class assignments but the cheapskate in me thinks it might be better to move to Bitbucket which has free & unlimited private repos. 

Edit: Problem 6 was relatively straightforward and I solved that quickly. It requires summation formula which, if you’ve taken Calculus I or Discrete Math, should be easy to do. I’ve pushed it to the Github repo which contains  all my solutions. 

https://gist.github.com/1522780

Edit: Problem 7 is done.

https://gist.github.com/1522955

Code Critiques

So, I finished the semester on a strong note: aced all 4 of my classes. Woohoo! 

The relevant CS courses I took were: Intro to Programming (using Java), Discrete Math and Calculus I. I heartily recommend this combination of classes because the concepts I learned in Discrete Math served me well in my Java class (think propositional & predicate logic) and my Calculus class (functions/relations)!

Project Euler

ProjectEuler is “a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve.” In other words, it is a collection of problems for inquiring minds.

I solved the first problem using Python and it was relatively straightforward

https://gist.github.com/1498226

The next problem (Problem 2) was solved with Java and it builds on skills you used for solving Problem 1 and adds the Fibonacci algorithm to the mix:

https://gist.github.com/1495500

I’ll be working on Problem 3 and will have my solution ready when it’s fit for public viewing.

Update: my solution is here. It’s bulky but it works. Phew.

https://gist.github.com/1499599