C# 101: Intro to C# Programming

Introduction

• Your Name• Your day job• Your last holiday destination?

C# 101

• C# Fundamentals– Setting up your development environment– Language Overview– How C# Works– Writing your first program– Built-in Data Types– Conditionals and Loops

C# 102

• Object-oriented Programming– Classes and Objects– Polymorphism, Inheritance and Encapsulation– Functions and Libraries

C# 103

• Data Structures– Arrays– Collections

C# 101: Introduction to C#

Setting up your Development Environment

Installing Integrated Development Kit

• Download latest VS IDE from https://www.visualstudio.com/en-us/downloads/download-visual-studio-vs.aspx

What is an IDE?

• IDE = Integrated Development Environment • Makes you more productive • Includes text editor, compiler, debugger,

context- sensitive help, works with different SDKs

• Visual Studio is the most widely used IDE

Installing Visual Studio

• Download and install the latest Visual Studio for .Net framework(64 Bit version) from https://www.microsoft.com/en-gb/download/details.aspx?id=30653

• To start Visual Studio– On PC, double-click on Visual Studio

Hands-on Exercise

Visual Studio Setup & Demo

C# 101: Introduction to C#

Language Overview

C# Language Overview

• Object-oriented• Widely available• Widely used

C# Versions • Brief History… - C#'s principal designer and lead architect at Microsoft is Anders Hejlsberg, was previously involved with the design of Pascal, Delphi and Visual J++

• Major Version Releases– C# 1.0 (2002)– C# 2.0 ( 2005)– C# 3.0 (2008)– C# 4.0 (2010)– C# 5.0 (2012)– C# 6.0 (2015)

Visual Studio Editions

• Visual Studio Standard Edition • Visual Studio Enterprise Edition• Visual Studio Community Edition• Visual Studio Express Edition

.NET FrameworkA programming infrastructure created by Microsoft for building, deploying, and running applications and services that use .NET technologies, such as desktop applications and Web services.

The .NET Framework contains three major parts: the Common Language Runtime. the Framework Class Library. ASP.NET.

.NET framework is required to develop and compile programs

Developers must have this installed

C# 101: Introduction to C#

How C# works

How C# Works

C# File Structure

C# 101: Introduction to C#

Writing Your First Program

Hello, World!

Writing Your First C# Program• Create a new project in your IDE named Csharp101• Create a HelloWorld class in the src folder inside the Csharp101 project as illustrated below. using System; namespace HelloWorldApplication { class HelloWorld { static void Main(string[] args) { /* my first program in C# */ Console.WriteLine("Hello World"); Console.ReadKey(); } } }

Compiling Your First Java Program• Save the HelloWorld class in the IDE• This automatically compiles the HelloWorld.cs file into

into a HelloWorld.class file• Go to the folder you created the csharp101 project on

your hard disk and open the src folder.• What do you see?

Running Your First C# Program

• Build and Run your program in Visual Studio by Ctrl+Shift+B / F5

Anatomy of a C# ApplicationComments Class Name

Access modifier

Function/static method

Arguments

Language Features

Introduction to C#

Built-in Data Types

Built-in Data Types• Data type are sets of values and operations

defined on those values.

Basic Definitions

• Variable - a name that refers to a value.• Assignment statement - associates a value with a

variable.

String Data Type

Data Type AttributesValues sequence of charactersTypical literals “Hello”, “1 “, “*”Operation ConcatenateOperator +

• Useful for program input and output.

String Data Type

String Data Type• Meaning of characters depends on context.

String Data Type

Expression Value“Hi, “ + “Bob” “Hi, Bob”

“1” + “ 2 “ + “ 1” “ 1 2 1”“1234” + “ + “ + “99” “1234 + 99”

“1234” + “99” “123499”

Hands-on Exercise

Command Line Arguments

Exercise: Command Line Arguments

• Create the C# program below that takes a name as command-line argument and prints “Hi <name>, How are you?”

namespace ConsoleApplication1{ class Program { static void Main(string[] args) { string x; System.Console.WriteLine("Enter your name"); x = Console.ReadLine(); System.Console.WriteLine("Hi {0} , How are you", x); Console.ReadKey();

} }}

Integer Data Type

Data Type Attributes

Values Integers between -2E31 to +2E31-1

Typical literals 1234, -99 , 99, 0, 1000000Operation Add subtract multiply divide remainder

Operator + - * / %

• Useful for expressing algorithms.

Integer Data TypeExpression Value Comment

5 + 3 85 – 3 25 * 3 155 / 3 1 no fractional

part5 % 3 2 remainder1 / 0 run-time error

3 * 5 - 2 13 * has precedence

3 + 5 / 2 5 / has precedence

3 – 5 - 2 -4 left associative(3-5) - 2 -4 better style3 – (5-2) 0 unambiguous

Double Data Type

• Useful in scientific applications and floating-point arithmetic

Data Type Attributes

Values Real numbers specified by the IEEE 754 standard

Typical literals 3.14159 6.022e23 -3.0 2.0 1.41421356237209

Operation Add subtract multiply divide

Operator + - * /

Double Data TypeExpression Value

3.141 + 0.03 3.171

3.141 – 0.03 3.111

6.02e23 / 2 3.01e23

5.0 / 2.0 1.6666666666667

10.0 % 3.141 0.577

1.0 / 0.0 Infinity

Math.sqrt(2.0) 1.4142135623730951

C# Math Library

Methods

Math.sin() Math.cos()Math.log() Math.exp()Math.sqrt() Math.pow()

Math.min() Math.max()Math.abs() Math.PI

http://java.sun.com/javase/6/docs/api/java/lang/Math.html

Hands-on Exercise

Integer Operations

Exercise: Integer Operations• Create a C# class named IntOps in the C101 project that performs integer operations

on a pair of integers from the command line and prints the results.

Solution: Integer Operationsint num1, num2, sum, prod, quot, rem;num1 = int.Parse(Console.ReadLine());num2 = int.Parse(Console.ReadLine());sum = num1 + num2; prod = num1 * num2; quot = num1 / num2; rem = num1 % num2;System.Console.WriteLine(" {0} : {1} = {2}", num1, num2, sum.ToString());System.Console.WriteLine(" {0} : {1} = {2}", num1, num2, prod.ToString());System.Console.WriteLine(" {0} : {1} = {2}", num1, num2, quot.ToString());System.Console.WriteLine(" {0} : {1} = {2}", num1, num2, rem.ToString());Console.ReadLine();

Boolean Data Type

• Useful to control logic and flow of a program.

Data Type Attributes

Values true or false

Typical literals true false

Operation and or not

Operator && || !

Truth-table of Boolean Operations

a !a a b a && b a || b

true false false false false false

false true false true false true

true false false true

true true true true

Boolean Comparisons

• Take operands of one type and produce an operand of type boolean.

operation meaning true false== equals 2 == 2 2 == 3!= Not equals 3 != 2 2 != 2< Less than 2 < 13 2 < 2

<= Less than or equal

2 <= 2 3 <= 2

> Greater than 13 > 2 2 > 13>= Greater than

or equal3 >= 2 2 >= 3

Type Conversion

• Convert from one type of data to another. • Implicit – no loss of precision– with strings

• Explicit: – cast – method.

Type Conversion Examplesexpression Expression type Expression value“1234” + 99 String “123499”

Int.Parse(“123”) int 123(int) 2.71828 int 2

Math.round(2.71828) long 3(int) Math.round(2.71828) int 3(int) Math.round(3.14159) int 3

11 * 0.3 double 3.3(int) 11 * 0.3 double 3.311 * (int) 0.3 int 0

(int) (11 * 0.3) int 3

Hands-on Exercise

Leap Year Finder

Exercise: Leap Year Finder

• A year is a leap year if it is either divisible by 400 or divisible by 4 but not 100.

• Write a java class named LeapYear in the Java101 project that takes a numeric year as command line argument and prints true if it’s a leap year and false if not

Solution: Leap Year Finder

int year = int.Parse(Console.ReadLine());

Boolean isLeapYear;

isLeapYear = (year % 4 == 0) && (year % 100 != 0); isLeapYear = isLeapYear || (year % 400 == 0);

System.Console.WriteLine("the Year {0} is {1} ", year.ToString(), isLeapYear.ToString());

Console.ReadLine();

Data Types Summary

• A data type is a set of values and operations on those values. – String for text processing– double, int for mathematical calculation– boolean for decision making

• Why do we need types? – Type conversion must be done at some level. – Compiler can help do it correctly. – Example: in 1996, Ariane 5 rocket exploded after takeoff

because of bad type conversion.

Introduction to C#

Conditionals and Loops

Conditionals and Loops

• Sequence of statements that are actually executed in a program.

• Enable us to choreograph control flow.

Conditionals

• The if statement is a common branching structure. – Evaluate a boolean expression.

• If true, execute some statements. • If false, execute other statements.

If Statement Example

if (Math.Sqrt(16) < 3) System.Console.WriteLine("the number is less than 3");Else System.Console.WriteLine("the number is greater than 3"); Console.ReadLine();

More If Statement Examples

While Loop

• A common repetition structure. – Evaluate a boolean expression. – If true, execute some statements. – Repeat.

For Loop• Another common repetition structure.

– Execute initialization statement. – Evaluate a boolean expression.

• If true, execute some statements. – And then the increment statement. – Repeat.

Anatomy of a For Loop

for (int i = 0; i < 5; i++) { System.Console.WriteLine("{0}", i); }

Console.ReadLine();

Hands-on Exercise

Powers of Two

Exercise: Powers of Two• Create a new C# project in Visual Studio named Pow2• Write a C# class named PowerOfTwo to print powers of 2 that are <= 2N

where N is a number passed as an argument to the program.– Increment i from 0 to N. – Double v each time

Solution: Power of 2

Control Flow Summary• Sequence of statements that are actually executed in a

program. • Conditionals and loops enable us to choreograph the

control flow. Control flow Description Example

Straight line programs

all statements are executed in the order given

Conditionals certain statements are executed depending on the values of certain variables

IfIf-else

Loops certain statements are executed repeatedly until certain conditions are met

while for

do-while

Homework Exercises

Java 101: Introduction to C#

Hands-on Exercise

Array of Days

Exercise: Array of Days

• Create a C# class named DayPrinter that prints out names of the days in a week from an array using a for-loop.

Solution: Arrays of Days

string[] daysOfTheWeek = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" }; for(int i= 0;i < daysOfTheWeek.Length ;i++){ System.Console.WriteLine("{0}", daysOfTheWeek[i]);}

Hands-on Exercise

Print Personal Details

Exercise: Print Personal Details

• Write a program that will print your name and address to the console, for example:

Alex Johnson23 Main StreetNew York, NY 10001 USA

Further Reading