C# Introduction

ISYS 350

Visual Studio 2010 Demo• Start page: New project/ Open project/Recent projects• Starting project:

• File/New Project/– C# – Windows

» Windows form application– Project name

• Project windows:– Form design view/Form code view– Solution Explorer

• View/Solution Explorer– Server Explorer– Property Window

• Properties and Events– ToolBox– Project/Add New Item– Property window example

Introduction to C#

• Event-driven programming– The interface for a C# program consists of one

or more forms, containing one or more controls (screen objects).

– Form and controls have events that can respond to. Typical events include clicking a mouse button, type a character on the keyboard, changing a value, etc.

– Event procedure

Form

• Properties:– Name, FormBorderStyle, Text, BackColor,

BackImage, Opacity

• Events:– Load, FormClosing, FormClosed– GotFocus, LostFocus– MouseHover, Click, DoubleCLick

Typical Controls

• TextBox• Label• Button• CheckBox• RadioButton• ListBox• ComboBox• PictureBox

Text Box• Properties:

– AutoSize, BorderStyle, CauseValidation, Enabled, Locked, Multiline, PasswordChar, ReadOnly, ScrollBar, TabIndex, Text, Visible, WordWrap, etc.

• Properties can be set at the design time or at the run time using code.

• To refer to a property: – ControlName.PropertyName– Ex. TextBox1.Text– Note: The Text property is a string data type and

automatically inherits the properties and methods of the string data type.

Typical C# Programming Tasks

• Creating the GUI elements that make up the application’s user interface.– Visualize the application.– Make a list of the controls needed.

• Setting the properties of the GUI elements

• Writing procedures that respond to events and perform other operations.

To Add an Event-Procedure

• 1. Select the Properties window

• 2. Click Events button

• 3. Select the event and double-click it.

• Note: Every control has a default event. • Form: Load event

• Button control: Click event

• Textbox: Text Changed event

– To add the default event procedure, simply double-click the control.

Demo

FirstName

LastName

FullName

.Control properties

.Event: Click, MouseMove, Form Load, etc.

.Event proceduresFullName: textBox3.Text textBox3.Text = textBox1.Text + " " + textBox2.Text;

Demo: Text alignment (TextAlign property)

Demo

Num1

Num2

Sum =

.Control properties

.Event: Click, MouseMove, Form Load, etc.

.Event proceduresSum: textBox3.Text = (double.Parse(textBox1.Text) + double.Parse(textBox2.Text)).ToString();

C# Project

• The execution starts from the Main method which is found in the Program.cs file.– Solution/Program.cs– Contain the startup code

• Example: Application.Run(new Form1());

Variable Names

• A variable name identifies a variable• Always choose a meaningful name for variables• Basic naming conventions are:

– the first character must be a letter (upper or lowercase) or an underscore (_)

– the name cannot contain spaces– do not use C# keywords or reserved words

• Variable name is case sensitive

Declare a Variable• C# is a strongly typed language. This means

that when a variable is defined we have to specify what type of data the variable will hold.

• DataType VaraibleName;• A C# statement ends with “;”

string DataType

• string Variables: • Examples:

string empName;string firstName, lastAddress, fullName;

• String concatenation: + • Examples:

fullName = firstName + lastName;MessageBox.Show(“Total is “ + 25.75);

Numeric Data Types

• int, double, decimal• Examples:

double mydouble=12.7, rate=0.07;int Counter = 0;

The decimal Data Type

• In C#, the decimal keyword indicates a 128-bit data type (16 bytes).

• Compared to double types, it has more precision and a smaller range, which makes it appropriate for financial and monetary calculations.

• Be sure to add the letter M (or m) to a decimal value:

decimal payRate = 28.75m;decimal price = 8.95M;

Inputting and Outputting Numeric Values

• Input collected from the keyboard are considered combinations of characters (or string literals) even if they look like a number to you

• A TextBox control reads keyboard input, such as 25.65. However, the TextBox treats it as a string, not a number.

• In C#, use the following Parse methods to convert string to numeric data types

– int.Parse– double.Parse– decimal.Parse

• Examples:int hoursWorked = int.Parse(hoursWorkedTextBox1.Text); double temperature = double.Parse(temperatureTextBox.Text);

Note: We can also use the .Net’s Convert class methods: ToDouble, ToInt, ToDecimal:Example: hoursWorked = Convert.ToDouble(textBox1.Text);

Explicit Conversion between Numeric Data Types with Cast Operators

• C# allows you to explicitly convert among types, which is known as type casting

• You can use the cast operator which is simply a pair of parentheses with the type keyword in it

int wholeNumber;decimal moneyNumber = 4500m;wholeNumber = (int) moneynumber;

double realNumber;decimal moneyNUmber = 625.70m;realNumber = (double) moneyNumber;moneyNumber=(decimal) realNumber;

Note: All variables come with a ToString() method.Note: We can also use the .Net’s Convert class methods

Example

double num1;int num2;decimal num3;num1 = Convert.ToDouble(textBox1.Text);num2 = Convert.ToInt16(textBox2.Text);num3 = Convert.ToDecimal(num1) + Convert.ToDecimal(num2);num3 = (decimal)num1 + (decimal)num2;textBox3.Text = num3.ToString();

Performing Calculations

• Basic calculations such as arithmetic calculation can be performed by math operators

Operator Name of the operator Description

+ Addition Adds two numbers

- Subtraction Subtracts one number from another

* Multiplication Multiplies one number by another

/ Division Divides one number by another and gives the quotient

% Modulus Divides one number by another and gives the remainder

Other calculations: Use Math class’s methods.

Example

int dividend, divisor, quotient, remainder; dividend = int.Parse(textBox1.Text); divisor = int.Parse(textBox2.Text); quotient = dividend / divisor; remainder = dividend % divisor; textBox3.Text = quotient.ToString(); textBox4.Text = remainder.ToString();

Change Machine to Return Smallest Number of Coins

int changes, quarters, dimes, nickles, pennies; changes = int.Parse(textBox1.Text); quarters = changes / 25; dimes = (changes % 25) / 10; nickles = (changes - quarters * 25 - dimes * 10) / 5; pennies = changes - quarters * 25 - dimes * 10 - nickles * 5; textBox2.Text = quarters.ToString(); textBox3.Text = dimes.ToString(); textBox4.Text = nickles.ToString(); textBox5.Text = pennies.ToString();

FV = PV * (1 +Rate) Year

double pv, rate, years, fv; pv = double.Parse(textBox1.Text); rate = double.Parse(textBox2.Text); years = double.Parse(textBox3.Text); fv = Math.Pow(pv * (1 + rate), years); textBox4.Text = fv.ToString();

Formatting Numbers with the ToString Method

• The ToString method can optionally format a number to appear in a specific way

• The following table lists the “format strings” and how they work with sample outputs

Format String

Description Number ToString() Result

“N” or “n” Number format 12.3 ToString(“n3”) 12.300

“F” or “f” Fixed-point scientific format 123456.0 ToString("f2") 123456.00

“E” or “e” Exponential scientific format 123456.0 ToString("e3") 1.235e+005

“C” or “c” Currency format -1234567.8 ToString("C") ($1,234,567.80)

“P” or “p” Percentage format .234 ToString("P") 23.40%

Working with DateTime Data

• Declare DateTime variable:– Example: DateTime mydate;

• Convert date entered in a textbox to DateTime data:– Use Convert:

• mydate = Convert.ToDateTime(textBox1.Text);– Use DateTime class Parse method:

• mydate = DateTime.Parse(textBox1.Text);

Comments

• Line comment: //// my comment

• Block comment: /* …… *//* comment 1

Comment 2…Comment n */