Advanced Programming

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Advanced Programming
C Introduction
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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

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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!" )
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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

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Constructions of Note

• static void Main()
• Defines the entry point for an assembly.
• Four different overloads taking string
  arguments and returning ints.
• Console.Write(Line)
• Takes a formatted string Composite Format
• Indexed elements e.g., 0
• can be used multiple times
• only evaluated once
• index ,alignmentformatting

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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

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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)

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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"
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Programs

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

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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
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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
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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
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Predefined Typesdecimal

• 128 bits
• Essentially a 96 bit value scaled by a power of
  10
• Decimal values represented precisely
• Doesnt support signed zeros, infinities or NaN

C Type System Type Size (bytes)
decimal System.Decimal 16
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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)
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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
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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
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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 string10
• Delegates delegate void Empty()

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Example

• Assume 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.

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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

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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 _at_

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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 way

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

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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 (_at_)

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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
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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.

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Program StructureNamespaces
namespace N1     // N1 class C1    //
N1.C1 class C2    // N1.C1.C2    
    namespace N2     // N1.N2 class C2
// N1.N2.C2        
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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 implicit N1.C1
b // Fully qualified name C2 c // Error! C2
is undefined N1.N2.C2 d // One of the C2
classes C1.C2 e // The other one
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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(He
llo 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!" )

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StatementsOverview

• Loop Statements
• while
• do
• for
• foreach
• Jump Statements
• break
• continue
• goto
• return
• throw
• Exception handling
• try
• throw

• Statement lists
• Block statements
• Labeled statements
• Declarations
• Constants
• Variables
• Expression statements
• checked, unchecked
• lock
• using
• Conditionals
• if
• switch

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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!
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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 Methods
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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.

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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.