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Midterm Exam 2019/10/24

The midterm exam will be held in class on Thursday 2019/10/24. You will not be allowed to use any reference while taking the exam. Bring a pen. You can leave class when you're done.

If you think the answer is different than you think I think it is, make a note why you think I think you're wrong and why you think you think you're right.

Reference vs Value types

Write an R or V to indicate if these Types are Reference types or Value types :

  • int
  • int[]
  • string
  • bool
  • Cat
  • Dictionary

Linq

Write one English sentence for each, what do these linq statements do?

students.Count(s => s.Grade > 70);
students.Select(s => s.Name).ToArray();
students.OrderByDescending(s => s.Grade).Take(5).Min(s => s.Age);
students.GroupBy(s => s.Gender).OrderByDescending(g => g.Average(s => s.Grade)).First().Key;

Classes from JSON

Design c# classes to form a data model which fits the structure of this json.

Reminder: This is what a class looks like:

public class Cat
{
	public string Name;
	public int AttackPoints;
	public Dog[] Targets;
}
{
    "chemicals": [
        {
            "name": "Ground Black Pepper",
            "safetyDataSheet": "http://archpdfs.lps.org/Chemicals/Black_pepper.pdf",
            "LD50": 200,
            "hazards": [
                {
                    "condition": "eyes",
                    "response": "rinse immediately"
                }, {
                    "condition": "spilled",
                    "response": "vacuum or sweep"
                },
            ]
        }, {
            "name": "Vinegar",
            "safetyDataSheet": "http://archpdfs.lps.org/Chemicals/Vinegar.pdf",
            "LD50": 3310,
            "hazards": [
                {
                    "condition": "ingested",
                    "response": "do not give baking soda"
                }
            ]
        }
    ]
}

URL Parts

Identify the parts of this URL. Assume that the webserver is configured in the conventional way.

  • Circle each individual parameter key-value pair
  • Draw a Box around the domain (including the sub-domain and top-level domain)
  • Strike through the path to the controller (including the controller)
  • Underline the action
  • Draw a happy cat sitting on top of the protocol
https://bb.courses.maine.edu/webapps/blackboard/execute/modulepage/view?course_id=_119158_1&cmp_tab_id=_260715_1&editMode=true&mode=cpview

IDisposable

If you are instantiating something which implements the IDisposable interface, you should probably wrap it in a __________________ statement to make sure that it gets ______________ when you're done with it.

HTTP Response Codes

Draw lines connection the HTTP response code to the basic meaning.

2xx			The client messed up
3xx			Everything is Fine
4xx			Sure, but it's over there
5xx			The server messed up

Code Review

Study this code sample from "your coworker" (line numbers are on the left):

public static class Math
{
0	private static double standardDeviation;
1	public static double CalculateStandardDeviation(int[] values)
2	{
3		var sum = 0;
4		int total = 0;
5
6		for (int i = 0; i <= values.Length; i++)
7		{
8			sum = sum + values[i];
9		}
10
11		var max = sum / values.length;
12		// This is the deviation sum.
13		int deviationSum = 0;
14
15		foreach (var value in values)
16		{
17			deviationSum = deviationSum + (int)Math.Abs(value - max);
18		}
19
20		standardDeviation = deviationSum / values.length;
21		Console.WriteLine("The standard deviation is: " + standardDeviation);
22
23		return standardDeviation;
24	}
}

Given the above code sample, for each of these problems: write a line number where the problem occurs, why it is wrong and suggest how they can improve it. Hint: Yes, it has each of these issues. You only need to reference one example of the problem.

  • uninformative or misleading names

  • inappropriate scope

  • unused things

  • comments that don't add any value

  • integer division

  • division by 0

  • index out of bounds

  • manual re-implementation of functionality which is in the system libraries

  • "magic" (hard-coded) numbers or strings

  • inconsistent code style

  • User Interface code mixed with Business Logic code

  • using the wrong type

  • casting (to try to fix the problem caused by using the wrong type)

  • "tricky" code without a unit test

  • any other sins? (Extra credit, because maybe I missed something)

Gramma

Gramma just sent me this email. Please compose a short response using at least these words: [Web browser, request, parameters, URL, network, server, model, view, controller, response, headers, body]

From: Ruth ****** <******@gmail.com>
Subject: Re: Checking In
To: Alex Hennings <alex.hennings@maine.edu>
Content-Type: text/plain; charset="UTF-8"

Grandson Alex:  Thanks for your reply and info re preferred mailing address - duly noted (look for mail from me).

Re "building Web Sites", can you explain in terminology I may understand what is a website and how does it work?

Am glad the teaching is working out for YOU - continue to be pondering new material; your students are depending on YOU!!   Hugs, Gma

Git

Write a short description of what the .gitignore file is for and why someone would choose to use it.