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Advanced Programming

C#

Introduction

Application Types

Console Application Has standard streams (out, in, err) GUI can be added manually

Windows Application GUI based No standard streams (out, in, err) Main thread is shared by the GUI message pump & your

code

Service No standard streams (out, in, err) Main thread is commandeered by the SCM No GUI

Start Visual Studio

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New Project

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Windows Application

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Simple Program – console application// A first program in C#.

using System;

class Welcome1

{

static void Main( string[] args )

{

Console.WriteLine( "Welcome to C# Programming!" );

} }

Constructions of Note

using like import in Java: bring in namespaces

namespace disambiguation of names like Internet hierarchical names and C++

naming class

like in C++ or Java single inheritance up to object

Constructions of Note

static void Main() Defines the entry point for an assembly. Four different overloads – taking string

arguments and returning int’s. 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]}

Common Type System (CTS)

From MSDN

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Atomic Data

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Simple Program: Add Integers

Primitive data types Data types that are built into C#

string, int, double, char, long

Console.ReadLine() Used to get a value from the user input

Int32.Parse() Used to convert a string argument to an integer Allows math to be preformed once the string is

converted

Built-in Types C# predefined types

The “root” object Logical bool Signed sbyte, short, int, long Unsigned byte, ushort, uint, ulong Floating-point float, double, decimal Textual char, string

Textual types use Unicode (16-bit characters)

Types Unified Type System

Value types Directly contain data Cannot be null

Reference types Contain references to objects May be null

int i = 123;string s = "Hello world;"

123i

s "Hello world"

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Programs

Write a C program to read three integer numbers and find their average.

Predefined TypesValue Types

All are predefined structs

Signed sbyte, short, int, long

Unsigned byte, ushort, uint, ulong

Character char

Floating point float, double, decimal

Logical bool

Predefined TypesIntegral Types

C# Type System Type Size (bytes) Signed?

sbyte System.Sbyte 1 Yes

short System.Int16 2 Yes

int System.Int32 4 Yes

long System.Int64 8 Yes

byte System.Byte 1 No

ushort System.UInt16 2 No

uint System.UInt32 4 No

ulong System.UInt64 8 No

Predefined TypesFloating Point Types

Follows IEEE 754 specification Supports ± 0, ± Infinity, NaN

C# Type System Type Size (bytes)

float System.Single 4

double System.Double 8

Predefined Typesdecimal

128 bits Essentially a 96 bit value scaled by a

power of 10 Decimal values represented precisely Doesn’t support signed zeros, infinities

or NaN

C# Type System Type Size (bytes)

decimal System.Decimal 16

Predefined Typesbool

Represents logical values Literal values are true and false Cannot use 1 and 0 as boolean values

No standard conversion between other types and bool

C# Type System Type Size (bytes)

bool System.Boolean 1 (2 for arrays)

Predefined Typeschar

Represents a Unicode character Literals

‘A’ // Simple character ‘\u0041’ // Unicode ‘\x0041’ // Unsigned short

hexadecimal ‘\n’ // Escape sequence character

C# Type System Type Size (bytes)

Char System.Char 2

Predefined Typesstring

An immutable sequence of Unicode characters

Reference type Special syntax for literals

string s = “I am a string”;

C# Type System Type Size (bytes)

String System.String 20 minimum

Type System Value types

Primitives int i; Enums enum State { Off, On } Structs struct Point { int x, y; }

Reference types Classes class Foo: Bar, IFoo {...} Interfaces interface IFoo: IBar {...} Arrays string[] a = new string[10];

Delegates delegate void Empty();

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ExampleAssume you work for the Alexandria

Electricity company and you need a program to help you calculate the electricity bill for each customer. The program input should be the old meter reading and the new meter reading. Given that the price is 0.10 pounds per kilowatt.

Program StructureMain Method

Execution begins at the static Main() method

Can have only one method with one of the following signatures in an assembly static void Main() static int Main() static void Main(string[] args) static int Main(string[] args)

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C#

Comments

Comments can be created using //…

Multi-lines comments use /* … */

Comments are ignored by the compiler

Program StructureSyntax

Identifiers Names for types, methods, fields, etc. Must be whole word – no white space Unicode characters Begins with letter or underscore Case sensitive Must not clash with keyword

Unless prefixed with @

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Identifiers: Keywords

Often we use special identifiers called keywords that already have a predefined meaning in the language Example: class

A keyword cannot be used in any other wayC# Keywords

abstract as base bool break byte case catch char checked class const continue decimal default delegate do double else enum event explicit extern false finally fixed float for foreach get goto if implicit in int interface internal is lock long namespace new null object operator out override params private protected public readonly ref return sbyte sealed set short sizeof stackalloc static string struct switch this throw true try typeof uint ulong unchecked unsafe ushort using value virtual void volatile while

All C# keywords are lowercase!

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Arithmetic

Arithmetic operations

Asterisk (*) is multiplication

Slash (/) is division

Percent sign (%) is the modulus operator

Plus (+) and minus (-) are the same

There are no exponents

OperatorsAssociativity

Assignment and ternary conditional operators are right-associative Operations performed right to left x = y = z evaluates as x = (y = z)

All other binary operators are left-associative Operations performed left to right x + y + z evaluates as (x + y) + z

Use parentheses to control order

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C#

Keywords

Words that cannot be used as variable or

class names

Have a specific unchangeable function

within the language

Example: class

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C# Classes

Class names can only be one word long (i.e. no white space in class name )

Class names are capitalized, with each additional English word capitalized as well (e.g., MyFirstProgram )

Each class name is an identifier Can contain letters, digits, and underscores (_) Cannot start with digits Can start with the at symbol (@)

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C# Class

Class bodies start with a left brace ({) Class bodies end with a right brace (})

Methods Building blocks of programs The Main method

Each console or windows application must have exactly one

All programs start by executing the Main method Braces are used to start ({) and end (}) a

method

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C# Statements

Anything in quotes (“) is considered a string

Every statement must end in a semicolon (;)

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C#

Escape sequence Description \n Newline. Position the screen cursor to the beginning of the

next line. \t Horizontal tab. Move the screen cursor to the next tab stop. \r Carriage return. Position the screen cursor to the beginning

of the current line; do not advance to the next line. Any characters output after the carriage return overwrite the previous characters output on that line.

\\ Backslash. Used to print a backslash character. \" Double quote. Used to print a double quote (") character. Some common escape sequences.

NameSpaces

You import namespaces when you want to be able to refer to classes by their short name, rather than full name

For example, import System.XML allows XmlDataDocument and XmlNode rather than System.XML.XmlDataDocument and System.XML.XmlNode to be in your code.

Program StructureNamespaces

namespace N1 {     // N1 class C1 {   // N1.C1 class C2 {   // N1.C1.C2 }     }     namespace N2 {    // N1.N2 class C2 { // N1.N2.C2     }     } }

Program StructureNamespaces

The using statement lets you use types without typing the fully qualified name

Can always use a fully qualified name

using N1;

C1 a; // The N1. is implicitN1.C1 b; // Fully qualified name

C2 c; // Error! C2 is undefinedN1.N2.C2 d; // One of the C2 classesC1.C2 e; // The other one

Program StructureNamespaces

Best practice: Put all of your types in a unique namespace

Have a namespace for your company, project, product, etc.

Look at how the .NET Framework classes are organized

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Namespaces Partition the name space to avoid name conflict! All .NET library code are organized using namespaces! By default, C# code is contained in the global

namespace To refer to code within a namespace, must use

qualified name (as in System.Console) or import explicitly (as in using System; )

using System;

class HelloWorld

{

static void Main(string[] args)

{

Console.WriteLine(“Hello World!”);

}

}

class HelloWorld

{

static void Main(string[] args)

{

System.Console.WriteLine(“Hello World!”);

}

}

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Welcome4.cs

// Printing multiple lines in a dialog Box.

using System;

using System.Windows.Forms;

class Welcome4

{

static void Main( string[] args )

{

MessageBox.Show( "Welcome \n to \n C# \n programming!" );} }

StatementsOverview

Statement lists Block statements Labeled statements Declarations

Constants Variables

Expression statements checked, unchecked lock using

Conditionals if switch

Loop Statements while do for foreach

Jump Statements break continue goto return throw

Exception handling try throw

StatementsExpression Statements

Statements must do work Assignment, method call, ++, --, new

static void Main() { int a, b = 2, c = 3; a = b + c; a++;Console.WriteLine(a + b + c); a == 2; // ERROR!}

Events

Events are a way for an object to communicate with those that are interested in what it has to offer, like a button has a click event

Interested parties use Event Handlers, which are a way of subscribing to the event

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Math Class Methods The Math class

Allows the user to perform common math

calculations

Using methods

ClassName.MethodName( argument1, arument2, … )

Constants

Math.PI = 3.1415926535…

Math.E = 2.7182818285…

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Math Class MethodsMethod Description Example Abs( x ) absolute value of x Abs( 23.7 ) is 23.7

Abs( 0 ) is 0 Abs( -23.7 ) is 23.7

Cos( x ) trigonometric cosine of x (x in radians)

Cos( 0.0 ) is 1.0

Exp( x ) exponential method ex Exp( 1.0 ) is approximately 2.7182818284590451 Exp( 2.0 ) is approximately 7.3890560989306504

Log( x ) natural logarithm of x (base e) Log( 2.7182818284590451 ) is approximately 1.0 Log( 7.3890560989306504 ) is approximately 2.0

Max( x, y ) larger value of x and y (also has versions for float, int and long values)

Max( 2.3, 12.7 ) is 12.7 Max( -2.3, -12.7 ) is -2.3

Min( x, y ) smaller value of x and y (also has versions for float, int and long values)

Min( 2.3, 12.7 ) is 2.3 Min( -2.3, -12.7 ) is -12.7

Pow( x, y ) x raised to power y (xy) Pow( 2.0, 7.0 ) is 128.0 Pow( 9.0, .5 ) is 3.0

Sin( x ) trigonometric sine of x (x in radians)

Sin( 0.0 ) is 0.0

Sqrt( x ) square root of x Sqrt( 900.0 ) is 30.0 Sqrt( 9.0 ) is 3.0

Tan( x ) trigonometric tangent of x (x in radians)

Tan( 0.0 ) is 0.0

Example

A motor car uses 8 liters of fuel per 100

km on normal roads and 15% more fuel

on rough roads. Write a program to

print out the distance the car can travel

on full tank of 40 liters of fuel on both

normal and rough roads.

StatementsVariables and Constants

static void Main() { const float pi = 3.14f; const int r = 123; Console.WriteLine(pi * r * r);

int a; int b = 2, c = 3; a = 1; Console.WriteLine(a + b + c);}

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Example

Write a program to ask you for the temperature in Fahrenheit and then convert it to Celsius. Given:C= 5/9 (F-32)

Write a program to ask you for the temperature in Celsius and then convert it to Fahrenheit.

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Programs

Write a program to ask a person for his

height in feet and inches and then tell them

his height in cms. Given that 1 foot = 30 cms

and 1 inch = 2.5 cms.

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Examples

Write a program to ask the user for the width and length of a piece of land and then tell him how many orange trees he can grow on it. Given that each orange tree requires 4 m2.

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Examples

Write a program to ask the user for the radius of a circle, and then display its area and circumference.