C# Introduction ISYS 350

Visual Studio 2012 Demo Start page: New project/ Open project/Recent projects Starting project: File/New Project/ –C# –Windows »Windows form application –Project name/Project folder Project windows: –Form design view/Form code view –Solution Explorer View/Solution Explorer –ToolBox –Property Window Properties and Events –Server Explorer –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

Common 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 procedures FullName: textBox3.Text textBox3.Text = textBox1.Text + " " + textBox2.Text; Demo: Text alignment (TextBox3.TextAlign=HorizontalAlign.Right) TextBox3.BackColor=Color.Aqua;

Demo Num1 Num2 Sum =.Control properties.Event: Click, MouseMove, Form Load, etc..Event procedures Sum: 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 “ );

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 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 decimalNumber = 4500m; wholeNumber = (int) decimalNumber; double doubleNumber; decimal decimalNumber = m; doubleNumber = (double) decimalNumber; DecimaNumber=(decimal) doubleNumber; 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 OperatorName of the operatorDescription +AdditionAdds two numbers -SubtractionSubtracts one number from another *MultiplicationMultiplies one number by another /DivisionDivides one number by another and gives the quotient %ModulusDivides 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(); Note: The result of an integer divided by an integer is integer. For example, 7/2 is 3, not 3.5.

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 = pv*Math.Pow(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 DescriptionNumberToString()Result “N” or “n”Number format12.3ToString(“n3”) “F” or “f”Fixed-point scientific format ToString("f2") “E” or “e”Exponential scientific format ToString("e3")1.235e+005 “C” or “c”Currency format ToString("C")($1,234,567.80) “P” or “p”Percentage format.234ToString("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); DateTime variable’s properties and methods

DateTime Example DateTime myDate; myDate = DateTime.Parse(textBox1.Text); MessageBox.Show(myDate.ToLongDateString());

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