Introduction to the C# Programming Language for the VB Programmer

Introduction to the C# Programming

Language for the VB Programmer

Lecture Overview Some key terms Introduce the C# programming

language for the VB developer Mention some important features of the

Visual Studio .NET environment Pass along some editing tips and tricks

Key Terms (1) Constructor – A special method that is called

when an object is created from its class In C# a method having the same name as it’s

class Class – A template from which objects are

created Inheritance – The concept that one class can

be created based on another class The TextBox class, for example

Method – An action that the object can perform

The SetFocus method of a TextBox, for example Property – The data stored in object.

The Text property of a text box, for example

Key Terms (2) Object – A class instance. Once an

object has been created from its class, it’s possible to call methods and read and write properties Objects are created when a class’

constructor is called Note that some classes are static and

have static methods

Project Structure Everything is the same as VB

Solution file, project file, program files

Modules have a file suffix of .cs instead of .vb

THE BIG DIFFERENCE

C# IS CASE

SENSITIVE

Statements In C#, all statements end with a semicolon ;

Statements can span multiple lines There is no need for a continuation character

as in VB C# example

System.Console.WriteLine( “This is a line of text”);

VB exampleSystem.Console.WriteLine( _ “This is a line of text”);

Comments XMLSummary comments begin with /// Single line comments are marked

with // Multi-line comments start with /* and

end with */

// A comment.

/* This is Also a comment */

Variable Declarations Variable declarations work the same

way in both C# and VB Local variables are declared inside of a

procedure Module-level variables are declared

outside of a procedure In C#, the declaration syntax is

reversed from VB

Variable Declaration (Examples) VB

Dim Count As IntegerDim MyName As String = “Ekedahl”

C#int count;string MyName = “Ekedahl”;

Variable Declarations (Examples) Access modifiers work the similarly in

VB and C# public, private, protected

VB syntax to declare a module-level variable Private Counter As Integer

C# syntax to declare the same variable private int Counter;

Data TypesC# VB

int Integer

bool Boolean

string String

double Double

float Single

date DateTime

Strings Use the System.String data type as in

VB; The C# string type maps to System.String

the string concatenation operator is + instead of &

The members are the same between C# and VB All this because these types are .net

Framework types

Type Conversion (Introduction) In IS 350, you used val to convert

strings to numbers In C#, val is used to declare implicitly

typed variables We will use a much different strategy

here Each primary data type supports a

method named TryParse The method accepts 2 arguments

The string to parse The output result

TryParse (Example) Try to parse the string arg and store the

result in outstring arg = "123";double result;if (System.Double.TryParse(arg, out result) == true)

{ return true;}return false;

Using System.Convert Members of System.Convert class also

convert one type to another System.Convert.ToInt32() System.Convert.ToDouble() System.Convert.ToDateTime() …

Constants Constants are just variables whose

value never changes Declare with the const statement Constants must be initialized when they

are declared

Constants (Example) Declare and initialize constants

const int x = 0;public const double gravitationalConstant = 6.673e-11;

private const string productName = "Visual C#";

Member Scope Access modifiers control the scope of a

procedure or variable The keywords are the same between VB and

C# private – scope is the class containing the

procedure or variable protected – scope is the current class and

derived class public – scope is global – exposed to other

assemblies

C# Blocks In VB, blocks are marked with keywords

Sub – End Sub If – End If Do – Loop While – End While

In C#, blocks are all marked with {} as in Java or C++

C# Blocks (Example)namespace Validate{ public static class ValidateNumbers { public static bool IsInteger( string arg) { } }}

Procedures Visual Basic has Function and Sub

procedures C# works a bit differently

Procedures that don’t return a value have a data type of void

Procedures that do return a value have an explicitly defined data type

Procedures (Example 1) The following procedure does not return

a value

private void InitializeLocal(){ // Statements}

Procedures (Example 2) The following procedure returns a value

having a data type of bool (Boolean)

public static bool IsInteger(string arg, out int result)

{ if (System.Int32.TryParse(arg, out result) == true) { return true; } return false;}

Calling Procedures To call a procedure, use it’s name If the argument list is empty, the () are

required The empty parens are optional in VB

Call the procedure foo without arguments

foo();

Operators (Arithmetic) Mathematical operators are the same

for both VB and C# with a few exceptions % is the modulus operator (Mod) ++ and -- are post and pre increment and

decrement operators

Increment Count (Example)Count++;

Operators (Logical) They are pretty much the same from VB

and C# Inequality (<>) in VB is (!=) in C# Equality (=) in VB is (==) in C#

In C#, the single (=) is always used for assignment statements

Relational Operators These are quite different

VB C#

And &

AndAlso &&

Or |

OrElse ||

Xor ^

Not !

Decision-Making Statements (if) if statements take a boolean

expression as an argument Note the parentheses are required

if (i >= 0){ // do something if i is // greater than 0}

Decision-Making Statements ( 2-way if) Use the else keyword to create a 2-way if statement

if ( i >= 0){ // Do something if i is // greater than 0.}else{ // Do something else.}

Decision-Making Statements ( multi-way if) Use else if to create multi-way decisions if (i > 0){ // Do something if i is // greater than 0.}else if (i < 0){ // Do something else.}else{

// i must be equal to 0.}

Decision-Making Statements (switch) C# uses the switch statement instead

of Select Case Both work the same way The break keyword must appear at the

end of each case

switch statement (Example)

switch (day){

case 0:DayOfWeek = “Sunday”;break;

case 1:DayOfWeek = “Monday”;break;

}

Loops (Introduction) while is used to create a pre-test loop

(Do While) do is used to create a post-test loop (Do Until)

for loops are used when the iteration count is known in advance

while Loops While loops take a boolean expression

enclosed in parenthesis The loop executes while the condition is

true {} mark the while block instead of End While

while Loops (Example)int i;while (i < 10){

System.Console.WriteLine(i);i++;

}

do Loops Do loops test the condition after the

loop has executed once Example:do { System.Console.WriteLine(x); x++; // Post increment operator} while (x < 5);

for Loops Like VB, for loops can be used when

the number of loop iterations is known in advance The syntax is quite different though

for Loops (Syntax)for ( init-expr; cond-expr; loop-expr ){ // statement block} int-expr contains the expression’s

initial value cond-expr contains the condition loop-expr updates the expression

for Loops (Example) Print the counting numbers from 1 to 10

for (int i = 0; i < 10; i++){

System.Console.WriteLine(i);}

foreach loops foreach loops are used to enumerate

arrays and collections We will talk about collections more later

When using a foreach loop you need not explicitly increment or decrement the counter

foreach loops (Example) Declare and enumerate a one-

dimensional array named fibarray

int[] fibarray = new int[] { 0, 1, 2, 3, 5, 8, 13 };

foreach (int i in fibarray){ System.Console.WriteLine(i);}

Exiting a Loop Prematurely Use the break statement to exit a loop Use the continue statement to jump to

the loop’s condition The condition is tested immediately

There is a goto statement to jump to a named label but we will NEVER use it

Importing and Using Namespaces By default, you must fully qualify class

and method names System.IO.StreamReader for example

In VB, the Imports statement allows unqualified references Imports System.IO

In C#, it’s the using statement using System.IO;

C# Arrays (Declaring) Arrays work similarly in both C# and VB

Instead of using a () for the subscript, use []

When declaring an array, the square brackets appear after the type

The above array is declared as an array of type int Note that

C# Arrays (Sizing) Arrays must be given a size before they

can be used The new keyword calls the array

constructor

C# Arrays (Initializing) Arrays can be initialized when they are

declared When declaring and initializing an array

in the same statement, you can omit the size as the value is inferred from the data

C# Arrays (Multidimensional) You saw 1-dimensional arrays in IS 350 Arrays can have 2, 3, or more

dimensions Declare a 2-dimensional array

Declare and size a 2-dimensional array

Accessing Array Members You access an array member via a

subscript Store the value 5 in the 4th array

element

2-dimensional arrays have two subscripts

C# Arrays (Jagged) C# supports jagged arrays but we will

not use them

ASP.NET Tables (Introduction) You used the <table> tag in IS 350 to

create static tables The <asp:table> element gives us a

rich interface

Introduction to the C# Programming Language for the VB Programmer

Documents

Transcript of Introduction to the C# Programming Language for the VB Programmer