Introduction to C#

Tom Roeder

CS 215 2006fa

(R01-2008Q4.me)

Goals of the course

Introduce C# language ECMA standard originally developed by MSR not just Java + C++ many extensions

Introduce .NET framework future of Windows base of Microsoft’s C# implementation

Non-goals

Teach you to program should be very comfortable writing OO code we will not cover much if any basic programming

Introduce object oriented languages not even teach you OO style (except wrt C#) expected to write all code in OO style

Give you a detailed grade S/U only even homework

S/U Details

Requirements for the course come to lecture participate do three assignments

Assignments are S/U will not be giving a detailed grade show me that you understand the concepts, and can write

C# code

All three assignments will be online soon must be completed by the end of the course

Administrative Details

Class time MWF 12:20-1:10 office hours: W 10:30-12 or by appointment

tmroeder@cs.cornell.edu (4112 Upson) Prerequisites: CS 211/212

really: experience in OO coding/concepts Academic Integrity

Do not submit work that is not your own minimum penalty: U in the course

Useful Tools

Visual C# Express: Google “Visual C# Express” in Visual Studio: MSDNAA

must be version 2005: we need C# 2.0

Mono: http://www.go-mono.com Open Source impl for Linux: not quite at 2.0

Rotor: http://msdn.microsoft.com/net/sscli Shared Source impl for Windows (through 2.0) Used to work on BSD / OS X, too

Useful Tools

Portable.NET: http://www.dotgnu.org yet another open source impl

CMS: http://cms.csuglab.cornell.edu we will use this for homework turn on your email notifications!

Course Webpage: http://www.cs.cornell.edu/courses/cs215 will post lectures online as well as any errata for the homework

CSUGLab

You all will have accounts MSDNAA access: let me know if you don’t

currently have it http://www.csuglab.cornell.edu/userinfo.html Visual Studio .NET 2005 should be installed there

Syllabus

Syllabus (10 more lectures) C# constructs: 5 lectures

Types, Delegates, Generics, Reflection, Iterators .NET Memory Management: 1 lecture Topics: 4 lectures

C# 3.0, Threading, Security, MSIL, MSH

Quiz 1

Each class will begin with a quiz not for credit but for knowledge but I will collect them and see what you know

Today’s quiz will be on prerequisites OO programming, mainly to do with Java If you don’t know Java, but do have OO

experience, it’s OK talk to me after if you have trouble

What is .NET?

A Framework in which to run code A Common Language Runtime (CLR)

runs all programs C# compiles to Microsoft Intermediate Language MSIL runs on CLR Virtual Machine like Java code written in many languages compiles to MSIL

A Common Language Specification (CLS) A Common Type System (CTS)

What is .NET?

Runtime

Operating System

.NET Framework

Common Type

System

Common Language Runtime

Building Blocks (e.g. for Services)

Services: .NET and COM+

SQL Server BizTalk ...

Languages:

C#, Visual Basic, etc

.NET Applications

Enterprise Servers

...Sharepoint ...

Web Services

From MSDN

What is the CLR?

Class Loader

MSIL to NativeCompilers (JIT)

CodeManager

GarbageCollector (GC)

Security Engine Debug Engine

Type Checker Exception Manager

Thread Support COM Marshaler

Base Class Library Support

From MSDN

What is the CTS?

A set of common types any language that runs in CLR should implement no syntax specified Languages often define aliases

For example CTS defines System.Int32 – 4 byte integer C# defines int as an alias of System.Int32

What is the CTS?

From MSDN

What is the CLS?

A specification of language features how methods may be called when constructors are called subset of the types in CTS are allowed

For example Code that takes UInt32 in a public method UInt32 is not in the CLS

Can mark classes as CLS-compliant not marked is assumed to mean not compliant

The Class Libraries

The common classes used in many programs like Java Class Library eg.

System.Console.WriteLine XML, Networking, Filesystem, Crypto, containers

Can inherit from many of these classes Many languages run on .NET framework

C#, C++, J#, Visual Basic even have Python (see IronPython)

Assemblies

Code contained in files called “assemblies” code and metadata .dll as before to run: public static void Main(string[] args) types

private: local directory, not accessible by others eg. Wolfram .NETLink

shared: well-known location, can be GAC strong names: use crypto for signatures

then can add some versioning and trust

COM vs .NET

Historically, COM provided this integration support for interfaces and interaction given a GUID, lookup the type library dynamically instantiate class do RPC to make calls in many cases

Difficult to get right software engineering problems not type safe at all

ASP.NET and ADO.NET

Use .NET languages in web pages thus can write typesafe code server-side or client-side Sharepoint interactions can log in

Use the CLR to access databases in the manner of ODBC provides classes for access

Windows PowerShell

New shell originally for MS Vista available for WinXP/2k3 native .NET

instantiates arbitary .NET classes and accesses them Also can access COM objects

Allows better interaction with programs Can it surpass bash and others?

First C# Program

using System;

namespace Test { int a = 137;

class Hello { public static void Main(string[] args) { Console.WriteLine(“Hello {0}”, a); } }

}

Constructions of Note

using like import in Java: bring in namespaces

namespace disambiguation of names like Internet hierarchical names and Java naming

class like in Java single inheritance up to object

Constructions of Note

Console.Write(Line) Takes a formatted string: “Composite Format” Indexed elements: e.g., {0}

can be used multiple times only evaluated once

{index [,alignment][:formatting]} also can use as in Java

“Test “ + a

More C# : basic inheritance

class A {

protected int a;

public virtual void print() {

Console.WriteLine(“a = “ + a);

}

}

class B : A {

public override void print() {

Console.WriteLine(“a really = “ + (a + 137));

}

}