	CS 683 Emerging Technologies Spring Semester, 2003 C# Intro
	Previous Lecture Notes Index © 2003, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 10-Apr-03

Contents of Doc 20, C# Intro

References
C# Language Specification, http://download.microsoft.com/download/0/a/c/0acb3585-3f3f-4169-ad61-efc9f0176788/CSharp.zip

Programming C#, Jesse Liberty, O’Reilly, Chapters 1-3


Doc 20, C# Intro Slide # 2

Compilers
Microsoft Visual Studio .NET

Mono http://go-mono.org/

Open source compiler and runtime for Linux

Shared Source Common Language Infrastructure (sscli)
Linux
Windows
Mac OS 10
Download
http://www.microsoft.com/downloads/details.aspx?FamilyId=3A1C93FA-7462-47D0-8E56-8DD34C6292F0&displaylang=en

Information
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/Dndotnet/html/mssharsourcecli.asp


Doc 20, C# Intro Slide # 3

C#

Another C-based object-oriented programming language

public class Hello
{
public static void Main()
{
//sample comment
System.Console.WriteLine( "hi");
/* another
comment */
}
}

using System;
public class Hello
{
public static void Main()
{
Console.WriteLine( "hi");
}
}


Doc 20, C# Intro Slide # 4

Naming Convention

Pascal Casing
Capitalize the first character of each word

SomeClassName

Camel Casing
Capitalize the first character of each word except the first word

someVariableName

Convention

Type	Case	Notes
Class	PascalCase
Attribute Class	PascalCase	Has suffix of Attribute
Exception Class	PascalCase	Has suffix of Exception
Constant	PascalCase
Enum type	PascalCase
Enum values	PascalCase
Event	PascalCase
Interface	PascalCase	Has a prefix of I
Method	PascalCase
Namespace	PascalCase
Property	PascalCase
Public Instance Field	PascalCase	Rarely used
Protected Instance Field	camelCase	Rarely used
Parameter	camelCase
Local variable	camelCase


Doc 20, C# Intro Slide # 5

Word choice

not use abbreviations in identifiers

you must use abbreviations, do use camelCase for any abbreviation containing more than two characters, even if this is not the usual abbreviation.

Classes

name classes with nouns or noun phrases

use PascalCase

use sparingly, abbreviations in class names

not use any prefix (such as “C”, for example)

Note no Hungarian notation

not use any underscores
<HR>

Parameters

use descriptive names such that a parameter’s name and type clearly imply its meaning

name parameters using camelCase

prefer names based on a parameter’s meaning, to names based on the parameter’s type

not use Hungarian-type prefixes


Doc 20, C# Intro Slide # 6

Methods

name methods with verbs or verb phrases

name methods with PascalCase

RemoveAll(), GetCharArray(), Invoke()


Doc 20, C# Intro Slide # 7

Case sensitivity

use names that require case sensitivity

C# is case sensitive

Components might need to be usable from both case-sensitive and case-insensitive languages


Doc 20, C# Intro Slide # 8

Avoiding type name confusion
Different languages use different names to identify the fundamental managed types

In a multi-language environment avoid language-specific terminology

use semantically interesting names rather than type names

the rare case that a parameter has no semantic meaning beyond its type, use a generic name.

For example use:
void Write(double value);
void Write(float value);
void Write(long value);
void Write(int value);
void Write(short value);

Rather than

void Write(double doubleValue);
void Write(float floatValue);
void Write(long longValue);
void Write(int intValue);
void Write(short shortValue);


Doc 20, C# Intro Slide # 9

Types

Built-in or base types
User-defined types

Value Types
Placed on stack

Base types, enum & struct

Reference Types
Placed on heap

Objects, arrays, delegate types


Doc 20, C# Intro Slide # 10

Built-in Types

Type	Description	Example
string	Unicode chars	string s = "hello";
sbyte	8-bit signed	sbyte val = 12;
short	16-bit signed	short val = 12;
int	32-bit signed	int val = 12;
long	64-bit signed	long val1 = 12; long val2 = 34L;
byte	8-bit unsigned	byte val1 = 12;
ushort	16-bit unsigned	ushort val1 = 12;
uint	32-bit unsigned	uint val1 = 12; uint val2 = 34U;
ulong	64-bit unsigned	ulong val1 = 12; ulong val2 = 34U; ulong val3 = 56L; ulong val4 = 78UL;
float	Single-precision	float val = 1.23F;
double	Double-precision	double val1 = 1.23; double val2 = 4.56D;
bool	Boolean type;	bool val1 = true; bool val2 = false;
char	Unicode char	char val = 'h';
decimal	Precise decimal type with 28 significant digits	decimal val = 1.23M;


Doc 20, C# Intro Slide # 11

Escape Sequences

Escape sequence	Character name	Unicode encoding
\'	Single quote	0x0027
\"	Double quote	0x0022
\\	Backslash	0x005C
\0	Null	0x0000
\a	Alert	0x0007
\b	Backspace	0x0008
\f	Form feed	0x000C
\n	New line	0x000A
\r	Carriage return	0x000D
\t	Horizontal tab	0x0009
\v	Vertical tab	0x000B

Unicode Escape Sequence
char sample = ‘\u0066’;


Doc 20, C# Intro Slide # 12

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	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
short	sizeof	stackalloc	static	string
struct	switch	this	throw	true
try	typeof	uint	ulong	unchecked
unsafe	ushort	using	virtual	void
volatile	while

Keywords as Identifiers
int @int = 3;

Prefixing an identifier with @ allows keywords to be used

@ is not part of the identifer

@cat is the same identifier as cat


Doc 20, C# Intro Slide # 13

Implicit Conversion Implicit cast to larger types

Must use explicit cast to smaller types

public static void Main()
{
char a = 'c';
int b = a;
a =(char) b;
a = b; //Compile error
int c = b;
}


Doc 20, C# Intro Slide # 14

Definite Assignment
Must assign a variable before using it


Doc 20, C# Intro Slide # 15

Constants

Literals
Constants
Enumerations

public class ConstantExample
{
public static void Main()
{
const int b = 5;
b = 4; //Compile error
}
}


Doc 20, C# Intro Slide # 16

Enumerations
enum Value
{
First = 1,
Second = 2,
Third, //gets value 2, indexing starts at 0
Fourth = 4,
}

class Hello
{

static void Main()
{
Value b = Value.Second;
b = (Value) 1;
b = b + 1;
b++;
System.Console.WriteLine( b);
}

enum Another :short
{
Foo = 2,
Bar = 3,
}
}


Doc 20, C# Intro Slide # 17

Basic Control Structures

if if (x == 5)
y = 9;

if (z > 3)
{
y = 10;
w = 1;
}
else
x = 2;


Doc 20, C# Intro Slide # 18

switch
const int Libertarian = 4;

int myChoice = Libertarian;
switch (myChoice)
{
case Democrat:
Console.WriteLine(“It all Bush’s fault”);
break;
case NewLeft:
goto case Progressive;
case LiberalRepublican:
case Republican:
Console.WriteLine(“We rule”);
break;
case Progressive:
Console.WriteLine(“Progress is best”);
break;
default:
Console.WriteLine(“Odd ones out”);
break; //Required
}


Doc 20, C# Intro Slide # 19

Swtich on Strings
string myChoice ="Libertarian";
switch (myChoice)
{
case "Democrat":
Console.WriteLine("It all Bush's fault");
break;
case "NewLeft":
goto case "Progressive";
case "LiberalRepublican":
case "Republican":
Console.WriteLine("We rule");
break;
case "Progressive":
Console.WriteLine("Progress is best");
break;
default:
Console.WriteLine("Odd ones out");
break;
}


Doc 20, C# Intro Slide # 20

goto
using System;

class GotoExample
{

static int Main()
{
int k = 0;
aLabel:
Console.WriteLine("K: " , k);
k++;
if (k < 10)
goto aLabel;
return 0;
}
}


Doc 20, C# Intro Slide # 21

While
using System;

class Hello
{

static int Main()
{
int k = 0;
while (k < 10)
{
Console.WriteLine("K: " , k);
k++;
}
return 0;
}

}


Doc 20, C# Intro Slide # 22

Do-While
using System;

class Hello
{

static int Main()
{
int k = 0;
do
{
Console.WriteLine("K: " , k);
k++;
}
while
(k < 10);
return 0;
}

}


Doc 20, C# Intro Slide # 23

for
using System;

class Hello
{

static int Main()
{
for(int k = 0; k < 10; k++)
{
Console.WriteLine("K: " , k);
}
return 0;
}

}


Doc 20, C# Intro Slide # 24

Continue & Break
break – exit the loop

continue – return to top of loop & start next iteration

using System;

class Hello
{

static int Main()
{
string input = Console.ReadLine();
for(int k = 0; k < 10; k++)
{
if (0 == k % 2 )
continue;
if (5 == k)
break;
Console.WriteLine("K: " , k);
}
return 0;
}
}


Doc 20, C# Intro Slide # 25

Operators & Precedence
Rows are ordered by precedence

Operators in top row have highest precedence

Category	Operators
Primary	x.y f(x) a[x] x++ x-- new typeof checked unchecked
Unary	+ - ! ~ ++x --x (T)x
Multiplicative	* / %
Additive	+ -
Shift	<< >>
Relational and type-testing	< > <= >= is as
Equality	== !=
Logical AND	&
Logical XOR	^
Logical OR	\|
Conditional AND	&&
Conditional OR	\|\|
Conditional	?:
Assignment	= *= /= %= += -= <<= >>= &= ^= \|=


Doc 20, C# Intro Slide # 26

Ternary Operator

class TernaryExample
{

static void Main()
{
int a = 5;
int b = 7;
int max = a > b ? a : b;
}
}


Doc 20, C# Intro Slide # 27

Preprocessor Directives

#define
#if
#elif
#else
#endif
#region
#endregion

Example #define DEBUG

class PreprocessorExample
{

static void Main()
{
int a = 5;

#if DEBUG
int b = 7;
#else
int b = 1;
#endif
int max = a > b ? a : b;
}

}


Doc 20, C# Intro Slide # 28

Region
Used by editors to fold text to show only the comment

class RegionExample
{

#region
/// <sumary>
///Comment for the
/// menthod below
/// </summary>
private void ComputeArea()
{
//blah
}
#endregion
}


Doc 20, C# Intro Slide # 29

Namespaces

namespace CS683
{
public class Hello
{

public static void max()
{
int a = 5;
int b = 7;
int max = a > b ? a : b;
}
}
}

class Test
{
static void Main()
{
CS683.Hello.max();
}
}


Doc 20, C# Intro Slide # 30

Nesting Namespaces
namespace CS683
{
namespace Examples
{
public class Hello
{
public static void max()
{
int a = 5;
int b = 7;
int max = a > b ? a : b;
}
}
}
}

class Test
{
static void Main()
{
CS683.Examples.Hello.max();
}
}

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2003 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA.
OpenContent license defines the copyright on this document.

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