Coding practice

Goal: Learn C# and ASP.NET MVC

We will build a self-checkout machine used in a supermarket together.

Task 2

TODO

Implement new requirements to store.rb and store_test.rb. Reading Ruby syntax will be useful to do this task.

Requirements

• Receipts show costs including cents (example: apple $5.00)

• Customers can purchase products which returns the receipt

store.Purchase(new string[] {"0001", "0002"}) //=>
apple $5.00
orange $10.00
total $15.00

• Owner can view purchase summary as data array

store.PurchaseSummary() //=>
[
  ["Time","Number of Products","Cost"],
  ["17/07/2015","2","20.00"],
  ["18/07/2015","1","15.99"]
]

• Owner can add discount to a product

store.AddDiscount("0001", 1) //=> $1 discount to product "0001"

• Owner can delete discount to a product

store.DeleteDiscount("0001") //=> delete discount to product "0001"

Task 1

TODO

git checkout task1

Create Store.cs to Countdown project

Create StoreTest.cs to Countdown.Tests project

TDD to implement requirements

Requirements

User can add an item to store

store.AddItem("0001", "apple", 10) // add $10 apple with barcode 0001

User can count stored items

store.ItemCount() //=> 10 (10 items)

User can calculate total cost of given items

store.CalculateCost(new string[] {"0001", "0001"}) //=> 20 (two apples costs $20)

User can print receipt of given items

store.PrintReceipt(new string[] {"0001", "0001"}) //=>
apple $10
apple $10
total $20

Setup environment

Install Visual Studio 2013

Here is basic ruby syntax useful to this task.

C# Syntax

Define Class

More info

class with no argument

public class Item
{
    public Item()
    {
    }
}

create with 1 argument

public class Item
{
    public Item(string name)
    {
    }
}

Create object

Item item1 = new Item();
Item item2 = new Item("apple");
var item2 = new Item("apple"); // var represent any type

instance variable (start with @)

public class Item
{
	private string name;
    public Item(string n)
    {
        name = n;
    }
    public print()
    {
    	Console.WriteLine(name);
    }
}
new Item("apple").print(); //=> "apple"

instance method

• declear method

public class Item
{
    public int price(int quantity)
    {
        return 10 * quantity;
    }
}
new Item("apple").print(); //=> "apple"

• call method

int price = new Item().price(5); //=> 50

Accessors

More info

• declear default accessors

public class Item
{
	// Use accessors if variable should be accessable from outside
	public string Name { get; set; } // name starts with capital letter
	public Item(string name)
	{
        Name = name;
    }
}
// Access data through set accessor
Item item = new Item("apple");
item.Name //=> "apple"

Condition

More info

• if statement

if (1 == 1)
{
    Console.WriteLine("case1");
}
else if (2 == 2)
{
    Console.WriteLine("case2");
}
else
{
    Console.WriteLine("case3");
}
end

• switch statement

switch (1)
{
    case 1:
        Console.WriteLine("case1");
        break;
    case 2:
        Console.WriteLine("case2");
        break;
    default:
        Console.WriteLine("default");
        break;
}

String

More info

• create string

string name = "apple";

• append string

string name = "apple";
Console.WriteLine(name + " orange"); //=> apple orange

• combine strings

string name = "apple";
Console.WriteLine("having {0}", name); //=> having apple

Array

More info

Array size can't be changed after initilized.

Values in Array can be changed.

• create array with data

string[] array = new string[] {"apple", "orange"};

• get length

string[] array = new string[] {"apple", "orange"};
array.Length; //=> 2

• change data

string[] array = new string[] {"apple", "orange"};
array[0] = "jazz apple";

• get index

string[] array = new string[] {"apple", "orange"};
Array.IndexOf(array, "apple"); // => 0
// Array class provides many methods used in List class

• shorten initializer

// new string[] can be skipped in this case (won't work with 'var array')
string[] array = {"apple", "orange"};

List

[More info](https://msdn.microsoft.com/en-us/library/6sh2ey19(v=vs.110) .aspx)

• create empty list

List<string> list = new List<string>();

• create list with data

List<string> list = new List<string>() {"apple", "orange"};

• add item to array

List<string> list = new List<string>();
list.Add("milk");

• get item by index

List<string> list = new List<string>() {"apple"};
list[0]; //=> "apple"

• find index of item

List<string> list = new List<string>() {"apple", "orange"};
list.IndexOf("apple"); //=> 0

• loop through each item

List<string> list = new List<string>() {"apple", "orange"};
foreach (string item in list)
{
	Console.WriteLine(item);
}
list.ForEach(item => Console.WriteLine(item)); // Short version

• map to create a new array with different value

List<int> list = new List<int>() {1, 2, 3};
List<int> newList = list.Select(item => item * 3); //=> [3, 6, 9]

• Inject to compose data

// update 0 5 times (0 -> 1 -> 3 -> 6 -> 10 -> 15) and return
List<int> list = new List<int>() {1, 2, 3, 4, 5};
int sum = list.Aggregate(0, (total, number) => total + number); //=> 15

Dictionary

More info

• namespace using System.Collections.Generic;

• create empty dictionary

Dictionary<string, int> dic = new Dictionary<string, int>();
// key => string, value => int 

• add key and value pair

Dictionary<string, int> dic = new Dictionary<string, int>();
dic.Add("key1", 100); // exception on exisiting key
dic["key1"] = 100;    // override value on existing key

• get value from key

Dictionary<string, int> dic = new Dictionary<string, int>();
hash = {"key" => "value"}
hash["key"] //=> "value" // exception to key not exist

UnitTesting

• namespace using Microsoft.VisualStudio.TestTools.UnitTesting;

• basic format

[TestClass]
public class StoreTest // Test Store class
{
    [TestInitialize]
    public void InitWithSomething()
    {
    	// Called before each test
    }
    [TestMethod]
    public void TestSomething()
    {
        // Single test
        Assert.AreEqual(2, 1 + 1);
    }
}

• assert two value

int expected = 2;
int actual = 1 + 1;
Assert.AreEqual(expected, actual);

• assert two lists

var a = new List<int> {1, 2, 3};
var b = new List<int> {1, 2, 3};
CollectionAssert.Equals(a, b);