C# basics

Basics of C# 2008 .NET 3.0/3.5

Session Objectives What is C#? Understand the basic structure of a C# program. Obtain a basic familiarization of what a "Namespace" is. Obtain a basic understanding of what a Class is. Learn what a Main method does. Learn how to obtain command-line input. Learn about console input/output (I/O).

Basic Structure of C# Program // Namespace Declaration using System; // Program start class class WelcomeCSS { // Main begins program execution. static void Main() { // Write to console Console.WriteLine("Welcome to the C# !"); } }

Getting Command-Line Input What is meant by command line arguments? How to take command line input? How to convert command line input to required type? Structure of Main() method in C#

Interactive via Command Line Taking input from user interactively Usage of Console.ReadLine() Conversion Functions

Object Oriented Programming Fundamentals Class Object Method Attribute Abstraction Encapsulation Polymorphism Inheritance Differences b/w object based and OO languages

Console Application in VS 2008 What is Solution (.sln)? IntelliSense Automatic Syntax checking Properties Window Solution Explorer Server Explorer

Basics Variables Initialization of Variables Scope of Variables Scope Clashes for Local Variables Scope Clashes for Fields and Local Variables Constants C# Data Types Value Types Reference Types

Integer Types Name CTS Type Description sbyte System.Sbyte 8-bit signed integer short System.Int16 16-bit signed integer int System.Int32 32-bit signed integer long System.Int64 64-bit signed integer byte System.Byte 8-bit unsigned integer ushort System.UInt16 16-bit unsigned integer uint System.UInt32 32-bit unsigned integer ulong System.UInt64 64-bit unsigned integer

Floating-Point Types Name CTS Type Description float System.Single 32-bit single-precision floating point double System.Double 64-bit double precision floating point

Decimal Type Name CTS Type Description decimal System.Decimal 128-bit high precision decimal notation

Boolean Type bool type can store either true/false.

Character Type Name CTS Type Description char System.Char 16-bit Unicode character

Escape Sequences Escape Sequence Character \’ Single quotation mark \” Double quotation mark \\ Backslash \0 Null \a Alert \b Backspace \f Form feed \n New line \r Carriage return \t Tab character \v Vertial tab

Predefined Reference Types Name CTS Type Description object System.Object The root type string System.String Unicode character string

Methods of Object Type Equals() GetHashCode() GetType() ToString()

Operators in C# Arithmetic +, -, *, /, % Logical &, |, ^, ~, &&, ||, ! Comparison ==, !=, <, >, <=, >= String Concatenation + Increment and Decrement ++, -- Bit Shifting (<<, >>) Assignment =, +=, -=, /=, %=, ^=, &=, |=, ^=, <<=, >>= Member Access .

Operators in C# (contd…) Indexing [] Casting ( ) Conditional ?: Delegate Concatenation and removal +,- Object Creation (new) Size information (sizeof, typeof, is, as) Overflow exception control (checked, unchecked) Namespace alias qualifier :: Operator Shortcuts

checked operator byte b=255; checked { b++; } Console.WriteLine(b.ToString()); When executed, it throws an Exception

unchecked operator byte b=255; unchecked { b++; } Console.WriteLine(b.ToString()); It won’t throw Exception. However, data would be lost.

is operator Used to check whether an object is compatible with a type. Eg: int x=10; if(x is object) Cosole.WriteLine(“x is an object”);

as operator Used to perform explicit type conversions of reference types. object o1=“Some String”; string s1=o1 as string;

sizeof operator Used to find size required by a type on stack. unsafe { Console.WriteLine(sizeof(int)); } Unsafe has to be used when we use pointers.

typeof operator Used to find the Sysem.Type object representing a specified type. Eg: Console.WriteLine(typeof(string));

Type Conversions Implicit Explicit

Flow Control Conditional Statements Loops Jump Statements

Conditional Statements if if – else if – else if – else switch

Loops while do… while for foreach

Jump Statements goto break continue return

Enumerations Example Switch example with enumeration

More on Compiling Options Option Output /t:exe A console application (default) /t:library A class library with manifest /t:module A component without a manifest /t:winexe A windows application (without a console window)

Console I/O Console.ReadLine() Console.WriteLine() Console.Read() ConsoleWrite()

Using Comments Internal Comments Single-line (//) Multiline (/* */) XML Documentation Comments (///) Csc /t:library /doc:Math.xml Math.cs

C# basics

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