Given an expression: 2 + ( ( 4 + 6 ) * (9 - 2) - 5 - 1) + 1 Write a program to calculate

Rails
1

Given an expression: 2 + ( ( 4 + 6 ) * (9 - 2) - 5 - 1) + 1

  1. Write a program calculate the given expression
  2. Do not simply use “eval” directly
  3. Need unit test

Bouns:
2 + ( ( 4 + 6 ) * sqrt(5) + 3) / 2 + 1

Here is my code http://chopapp.com/#1xrece1f, who can improve this for
me? Thank you!
Here is test code http://chopapp.com/#9w0u7ar4.

2

On Mon, Jan 5, 2015 at 8:35 AM, Qiangsheng W. [email protected]
wrote:

Given an expression: 2 + ( ( 4 + 6 ) * (9 - 2) - 5 - 1) + 1

  1. Write a program calculate the given expression

Is this homework for school or an interview?

–
Dave A., consulting software developer of Codosaur.us,
PullRequestRoulette.com, Blog.Codosaur.us, and Dare2XL.com.

3

Without an “x” in that expression I would argue that you don’t need (and
shouldn’t have) a unit test.

Now, if you add an “x” to that expression, then your unit test becomes
“Given value of X is ___, the result is ___” which makes a certain kind
of sense.

But without an “x”, all you’re testing is Ruby’s ability to parse, and
C’s ability to do math, which is certainly not within the scope of your
use case or domain.

Also I would argue that mathematically the part of the expression that
reads (9 - 2) - 5 - 1 is ambiguous in terms of algebra since you need to
know if the minus operation is “left order precedence” or “right order
precedence”. Personally I don’t have time in my workday to remember that
specific nuance of Ruby’s implementation of algebra and if this were a
Junior dev submitting a pull request I would make him or her add
parenthesis to eliminate that confusion.

Just my 2¢ on your post.

-Jason

Here is my code http://chopapp.com/#1xrece1f, who can improve this for me?
Thank you!
Here is test code http://chopapp.com/#9w0u7ar4.

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