01 Hello World
Programming fundamentals
YP0616 - YP0601
Elke Boonen & Tristan Vandevelde
1
Before we start!
Install Visual Studio on Windows
(community or enterprise)
https://visualstudio.microsoft.com/
https://www.academicsoftware.eu/dashboard
Install .NET desktop development:
--> console applications using C#.
Install Visual Studio on Mac
https://visualstudio.microsoft.com/vs/mac/
installation tutorial
2
Learning objectives (ECTS)
Basic principles (types, operators,
expressions) & structures (loop & if)
Arrays, lists, dictionaries
Methods and functions
Basic principles of OO
Files, in-and output IO
Exception handling
3
Learning materials
Canvas LMS https://thomasmore.instructure.com/
Presentations
E-Book: Fundamentals of Computer Programming with C#
Cheatsheet C#
Assigments (CodeGrade)
Online
https://docs.microsoft.com/en-us/dotnet/csharp/
https://github.com/ElkeBoonen/ProgrammingFundamentals (code from slides)
https://github.com/ElkeBoonen/ProgrammingFundamentals-Students (code from class)
Software
Visual Studio (Community) https://visualstudio.Microsoft.com/ 4
Schedule
Before autumn break After autumn break
01 Hello world 07 Exception handling
02 Variables & expression 08 Recap
03 If-structures 09 Collections
04 Loops 10 Methods
05 Files (IO) 11 OO
06 Arrays 12 OO
13 Exam prep
Schedule is always subject to unexpected circumstances 5
Evaluation
1st term
Permanent Evaluation (30 %):
CodeGrade exercises (each week, from week 02)
Computer Exam (70 %) use of cheatsheet only!
2nd term
Computer Exam (100 %) use of cheatsheet only!
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01 Hello world!
Why programming?
Why C#
Hello World!
Input/output
CodeGrade
7
What is an algorithm
A sequence of well-defined instructions
to perform a special task
Recipe
Solve a problem or perform a
computation
I am hungry! So we need bread!
Input to output
From ingredients to bread
8
What is a program?
A series of instructions performed by a computer
A program is always a combination of
sequences
selections
loops
methods
ready-made objects
objects you write yourself
9
What is a program?
Coding = translating algorithm to code
Programming = writing an algorithm in a
programming language
Programming is thinking!
The written program is converted to machine
language by
Compiler: transfer full program (eg: C#, Java...)
Interpreter: transfer line by line (eg: PHP, Python..)
Assembler: transfer to zeros and ones
10
Execution of program
Computer executes program step by step
A computer is very strict
Error in code = error in execution
11
Why should you learn to program?
“ Everybody in this country should learn
to program a computer, because it teaches https://www.youtube.com/embed
/uL3047AJRgk?enablejsapi=1
you how to think
- Steve Jobs -
12
From A# to Z++
Programming is only 50 years old
More than 700 programming languages!
Why is there not just one universal
language?
13
01 Hello world!
Why programming
Why C#
Hello World!
Input/output
CodeGrade
14
Why C#
It's not about the language,
it't about the algorithm!
But why C#?
Object oriented
Needs to be compiled
Well documented
Easier than C, C++ or Java
Just a good starting point for learning to code
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Visual Studio (community)
It's just the best IDE (Integrated Development Environment) in town!
Intellisense like code completion, quick info, member lists...
always remember CTRL+Space, just saying...
Download Visual Studio (Community) (also Mac-edition)
https://visualstudio.microsoft.com/
Install .NET desktop development: Build WPF, Windows Forms, and console
applications using C#.
16
01 Hello world!
Why programming
Why C#
Hello World!
Input/output
CodeGrade
17
Hello to the world!
First program!
first program in any programming language
just saying hi to the world!
Easy peasy lemon squeezy
Show text on screen
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First project
Open Visual Studio
Create a new project
Choose Console.App (.Net Core) C#
Mac-users : Apps - Console app
Project name: Hello World
Location: choose a location!
Solution: Create new solution
✔ Place solution and project in the same directory
Framework .NET 6.0
✔ Do not use top-level statements
Mac-users: choose .NET 3.1
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Take a look at the code
1 using System;
2
3 namespace HelloWorld Hit F5 or
4 {
5 internal class Program
6 {
7 static void Main(string[] args)
8 {
9 Console.WriteLine("Hello World!"); Terminal opens
10 }
11 } (press any key to close)
12 }
Hello World!
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Putting it out there
1 using System;
Prints text to output screen 2
3 namespace HelloWorld
Text must be placed between " " 4 {
5 class Program
Every line of simple code must end 6 {
7 static void Main(string[] args)
with semicolon ; 8 {
9 Console.WriteLine("Hello World!");
C# is case sensistive! 10
11 }
}
12 }
Try Console.Write(), what happens?
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Everything starts in Main
1 using System;
2
3 namespace HelloWorld
Main-method 4 {
5 class Program
Execution starts here! 6
7
{
static void Main(string[] args)
8 {
Main-method = code block 9 Console.WriteLine("Hello World!");
10 }
Everything inside block code 11 }
12 }
is surrounded by braces { }
Don't use ; after declaration of method or after { }
Main is mandatory in every C#-program
Everything inside Main will get executed
Add some extra writelines in Main, what happens?
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The class is half full
1 using System;
2
3 namespace HelloWorld
4 {
5 internal class Program
6 {
7 static void Main(string[] args)
8 {
9 Console.WriteLine("Hello World!");
10 }
11 }
12 }
Creates a class named Program!
internat = limited to the assembly in which it is declared
C# is object-oriented so creating a class is mandatory!
Every class is a code block, so code in class is surrounded by braces { }
Don't use ; after declaration of class or after { } 23
To namespace and beyond
1 using System;
2
3 namespace HelloWorld
4 {
5 class Program
6 {
7 static void Main(string[] args)
8 {
9 Console.WriteLine("Hello World!");
10 }
11 }
12 }
Creates a namespace HelloWorld (container for all associated classes)
A namespace is a code block, so content is surrounded by braces { }
Don't use ; after declaration of namespace or after { }
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To use or not to use
1 using System;
2
3 namespace HelloWorld
4 {
5 class Program
6 {
7 static void Main(string[] args)
8 {
9 Console.WriteLine("Hello World!");
10 }
11 }
12 }
Without using System we would write System.Console.WriteLine
The using-statement imports all functionality from the System namespace
which we need to print text to a screen.
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Computer says no
Your program won't run!
Message: there where build errors
Hit NO
Red wavy lines indicate the error
Start debugging by
reading the description of the error
Try to fix it! Test and re-test
“ Breathe in, breathe out, in any case never hit your computer!
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What's in a project
Find the project in file explorer
RMB project name in solution explorer,
select Open folder in File explorer )
HelloWorld.sln (solution le VS)
Program.cs (actual code)
bin (binary files, executable code)
obj (object files, temporary to build binary)
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Execute, make it happen!
Execute HelloWorld outside VS
Open executable in file explorer
navigate bin, debug, netcoreapp3.1, double-click HelloWorld.exe
Look closely, because it closes quickly.. Why?
Execute in terminal, open Powershell
1 > cd <navigate to project folder>
2 > cd bin
3 > cd .\Debug\
4 > cd .\netcoreapp3.1\
5 > .\HelloWorld.exe
6 Hello World!
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01 Hello world!
Why programming
Why C#
Hello World!
Input/output
CodeGrade
29
What is a variable?
Container for storing data values
Why do we need variables?
To store information given by the user as user input
To calculate and store intermediate results
To store information for later use
...
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Creating a variable
C# strongly typed variables: variable must be declared before using
What is declaring a variable?
give your variable a name
give your variable a type: C# has different primitive types!
What is initializing a variable?
give your variable its first value
Declaring and initializing can be done at the same time!
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String
C# type for text = string
text-value between " "
Always declare variable before use
type + name
Value of variable can change!
1 string text;
2 text = "some text";
3
4 string name = "Elke";
5 name = "Jan"
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Everything in the console is a string!
Everything on the command line is a piece of text = a string!
write to console = Console.WriteLine()
different ways of concatenating strings
read user input from console = Console.ReadLine()
store value given by the user in a variable for later use!
1 Console.WriteLine("What's your name?"); What's your name?
2
3 string name = Console.ReadLine(); ; Elke
4 Console.WriteLine($"Hello {name}!"); Hello Elke!
5 Console.WriteLine("Hello " + name + "!");
6 Console.WriteLine("Hello {0}!", name); Hello Elke!
Hello Elke!
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"No comment" is a comment
A comment is an explanation or annotation in the code
They are added to clarify code and are ignored by the compiler
1 //this is one line of comment
2
3 /*
4 These are mulitple lines of comment!
5 */
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01 Hello world!
Why programming
Why C#
Hello World!
Input/output
CodeGrade
35
We ❤ CodeGrade, yes we do!
Find the assignments in Canvas
Spend some hours to do them (plagiarism results in a 0!)
Submit (only) your .cs-file
Wait for your automatically generated result
Hit a home run? Do a little dance ;)
Not so successful? Tweak your solution and re-submit!
You can keep practicing until the deadline to become better, but also to score higher
points on your permanent evaluation
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01 Test CodeGrade
Go to Modules or Assignments
Find 01 Test CodeGrade
READ the assignment!
Create new project and solve assignment!
Upload program.cs-file of project
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Practice makes perfect!
Do your exercises, spend the hours!
The better the exercises, the better the exam!
Say what? How many hours?
6 SP = 6 * 28 hours = 168 hours
Lessons = 12 * 4 hours = 48 hours
Exam = 2 hours
Exercise = 168-48-2 = 118 hours
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