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Asked: 2024-11-26T07:52:06+00:00

C# Basic: From a javascript developer perspective

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As a Junior developer, i've always been scared of learning 'Old' programming language that primarily uses OOP paradigm. However, today I decided to suck it up and at least try it. It isn't as bad as I think, there's similarities that it carries over to Javascript. Let us go through the basics first.

This blog assumes understanding of javascript

The Basic

Data Types

Unlike javascript which is dynamically typed language, C# is statically typed language: The data type of a variable is known at the compile time which means the programmer has to specify the data type of a variable at the time of its declaration. 

int: number (32bit) decimal: number (128bit) string: string bool: Boolean list[]: Array dictionary{}: Object
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-------------- Declaration ---------------- int myInt = 2147483647; decimal myDecimal = 0.751m; // The m indicates it is a decimal string myString = "Hello World"; // Notice the double-quotes bool myBool = true;
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List/Array

Note: You cannot add or extend the length if you use method 1 & 2
Declaring & assigning List method 1 

string[] myGroceryArray = new string[2]; // 2 is the length myGroceryArray[0] = "Guacamole";
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Declaring & assigning List method 2 

string[] mySecondGroceryArray = { "Apples", "Eggs" };
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Declaring & assigning List method 3 

List<string> myGroceryList = new List<string>() { "Milk", "Cheese" }; Console.WriteLine(myGroceryList[0]); //"Milk" myGroceryList.Add("Oranges"); //Push new item to array
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Declaring & assigning Multi-dimensional List

The number of ',' will determine the dimensions 

string[,] myTwoDimensionalArray = new string[,] {     { "Apples", "Eggs" },     { "Milk", "Cheese" } };
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IEnumerable/Array

An array that is specifically used to enumerate or loop through.

You may ask, “What's the difference with list?”. The answer is:

One important difference between IEnumerable and List (besides one being an interface and the other being a concrete class) is that IEnumerable is read-only and List is not. 

List<string> myGroceryList = new List<string>() { "Milk", "Cheese" };  IEnumerable<string> myGroceryIEnumerable =  myGroceryList;
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Dictionary/Object 

Dictionary<string, string[]> myGroceryDictionary = new Dictionary<string, string[]>(){     {"Dairy", new string[]{"Cheese", "Milk", "Eggs"}} };  Console.WriteLine(myGroceryDictionary["Dairy"][2]);
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Operators

Operators in C# behaves very similar to javascript so I won't describe it here

Conditionals 

//Logic gate   //There's no === in C# myInt == mySecondInt  myInt != mySecondInt   myInt >= mySecondInt myInt > mySecondInt myInt <= mySecondInt  myInt < mySecondInt   // If Else if () {} else if () {} else () {}  // Switch switch (number) {     case 1:         Console.WriteLine("lala");         break;     default:         Console.WriteLine("default");         break; }
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Loops

🌟 Using foreach will be much faster than regular for loop

int[] intArr = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };  int totalValue = 0;  for (int i = 0; i < intArr.Length; i++) {     totalValue += intArr[i]; }  int forEachValue = 0;  foreach (int num in intArr) {     forEachValue += num; }
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Method

C# is first and foremost an OOP oriented language. 

namespace HelloWorld {     internal class Program     {         static void Main()         {             int[] numArr = [1, 2, 3, 4, 5];             int totalSum = GetSum(numArr);         }          static private int GetSum(int[] numArr)         {             int totalValue = 0;             foreach (var item in numArr)             {                 totalValue += item;             }             return totalValue;         }     } }
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Declaring Namespace & Model

Namespace is used to organization purpose, typically to organize classes 

namespace HelloWorld.Models {     public class Computer     {         public string Motherboard { get; set; } = "";         public int CPUCores { get; set; }         public bool HasWIfi { get; set; }         public bool HasLTE { get; set; }         public DateTime ReleaseDate { get; set; }         public decimal Price { get; set; }         public string VideoCard { get; set; } = "";     }; }
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Starting C# 10, we can also declare namespace as such 

namespace SampleNamespace;  class AnotherSampleClass {     public void AnotherSampleMethod()     {         System.Console.WriteLine(             "SampleMethod inside SampleNamespace");     } }
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Importing Namespace 

using HelloWorld.Models;
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