C# Introduction Part 1

Which Visual Studio Should I use?

• Any Express (2012, 2013…) or Community Edition 2013• Any full version

.Net framework

• Class Libraries …Console.ReadLine• MSIL• CLR

HelloWord, scope {}, method, Main, white space

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace First

{

class Program

{

static void Main(string[] args)

{

Console.WriteLine("Hello World!");

Console.ReadLine();

}

}

}

IDE, Projects, solutions, debug and release mode, …

C:\Users\<yourname>\Documents\Visual Studio 2013\Projects - default

Highly Recommend

Use C:\Projects\MIS118

.sln (open using Notepad -> it is xml)

Look at using .csproj

Debugging, Disable Squigglylines

Compiling

code.cpp

Assembly language

Machine language

.exe

C/C++old languages

C#.NET languages

com

pilin

gcode.cs

IntermediateLanguage (MSIL)

+ metadata

Machine language

.exe

C# compiler

JIT compiler

code.vb

VB.NET compiler

CommonLanguageRuntime

(CLR)

Command Line compile and execution

• C:\Windows\Microsoft.NET\Framework64\v4.0.30319• csc.exe• csc Program.cs

Comments, IntelliSense

// . . .

/* . . . */

Use Line numbers (Tools->Options)

Data Types, variables

x = 2

y = x + 1;

Console.WriteLine(y)

…

3

Need Variables

Data Types, variables (cont)

C# Variables Declaration and Naming

Primitives (though they are Objects)http://msdn.microsoft.com/en-us/library/ms228360(v=vs.90).aspx

object

String

Nullable Type (a bit advance)

King System.Object

char

stringint

Primitives are Objects

is Operator* (will be later again) static void Main(string[] args)

{

int myInt = 5;

TestIsOperator(myInt);

string myString = "5";

TestIsOperator(myString);

Console.ReadLine();

}

private static void TestIsOperator(Object obj)

{

if (obj is int)

{

int i = (int)obj;

Console.WriteLine("Integer received");

}

else if (obj is string)

{

string i = (string)obj;

Console.WriteLine("String received");

}

}

}

All are objects!!!

small integers (singed and unsinged)

big integers (singed and unsinged)

float and double, decimal

Special Floating numbers

(Division by 0)

Doubles vs Decimals

Ex: float and decimal* (again later)using System;using System.Collections.Generic;using System.Linq;using System.Text;

namespace DoubleVsDecimal{ class Program { static void Main(string[] args) { double a = 0.2f; double b = 1.0f;

Console.WriteLine("{0}", a - b);

decimal c = 0.2m; decimal d = 1.0m;

Console.WriteLine("{0}", c - d);

Console.ReadLine(); } }}output: -0.799999997019768-0.8

25

Characters and Strings

Strings methods* (again later)

Immutable String * (again later)

StringBuilder* (again later)

Variable Scope *(again later)

MyMethod

Type Conversion (cast)

Back to our example: using integer data type

int x = 2;

int y = x + 1;

Console.WriteLine(y);

Case sensitive language

string myName; myName = "Andrew"; Console.WriteLine(myName);

string myname = "Alice"; Console.WriteLine(myname);

one line

Introducing var

• Don’t be afraid

var myName1 = "Bill";

Conversion again* (again later). C# is a Strongly Typed Language

string s = "Angie"; int times = 100; Console.WriteLine(times + s);

string ok = times + s;

int bad = times + s;