C# Introduction

1. C# Introduction ISYS 350

2. Visual Studio 2017 Demo • Start page: New project/ Open project/Recent projects • Starting project: • File/New Project/ • Visual C# • Windows Classic Desktop • Windows Form App • Project name/Project folder

3. Project windows: • Form design view/Form code view • Solution Explorer • View/Solution Explorer • ToolBox (visible while in form design view) • View/ToolBox • Property Window • Properties and Events • Project/Add New Item • Property window example

4. 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

5. Form • Properties: • Name, FormBorderStyle, Text, BackColor, BackImage, Opacity • Events: • Load, FormClosing, FormClosed • GotFocus, LostFocus • MouseHover, Click, DoubleCLick

6. Common Controls • TextBox • Label • Button • CheckBox • RadioButton • ListBox • ComboBox • PictureBox

7. Text Box • Properties: • 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.

8. 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.

9. 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.

10. Demo FirstName LastName Show Full Name .Control properties .Event: Click, MouseMove, FormLoad, etc. .Event procedures FullName: textBox3.Text textBox3.Text = textBox1.Text + " " + textBox2.Text; Demo: Text alignment (TextBox3.TextAlign=HorizontalAlign.Right) TextBox3.BackColor=Color.Aqua;

11. Demo Num1 Num2 Compute Sum .Control properties .Event: Click, MouseMove, FormLoad, etc. .Event procedures Sum: textBox3.Text = (double.Parse(textBox1.Text) + double.Parse(textBox2.Text)).ToString(); In-Class lab: Show the product of Num1 and Num2.

12. C# Project’s Main Method • 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());

13. What does Variable mean? • A variable, in the context of programming, is a symbolic name given to an unknown quantity that permits the name to be used independent of the information it represents. • Variables are associated with data storage locations, and values of a variable are normally changed during the course of program execution.

14. 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

15. 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 “;”

16. string DataType • string Variables: • Examples: string empName; string firstName, lastAddress, fullName; • String concatenation: + • Examples: fullName = firstName + lastName; MessageBox.Show(“Total is “ + 25.75);

17. Numeric Data Types • int, double • Examples: double mydouble=12.7, rate=0.07; int Counter = 0; Other: decimal: decimal myMoney = 300.5m; float: float y = 4.5f;

18. 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 • 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);

19. 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 iNum1; double dNum1 = 2.5; iNum1 = (int) dNum1; Note: We can also use the .Net’s Convert class methods

20. Implicit conversion and explicit conversion int iNum1 = 5, iNum2 = 10; double dNum1 = 2.5, dNum2 = 7.0; dNum1 = iNum1 + iNum2; /*C# implicitly convert integer to double*/ iNum1 = (int) dNum1 * 2; /*from doulbe to integer requires cast operator*/

21. Performing Calculations • Basic calculations such as arithmetic calculation can be performed by math operators Other calculations: Use Math class’s methods.

22. Modulus Operator, % • Examples: • 7%2 • 25%4 • 7.5%2

23. 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.

24. Lab Exercise • Enter length measured in inches in a textbox; then show the equivalent length measured in feet and inches. • For example, 27 inches is equivalent to 2 feet and 3 inches.

25. 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();

26. 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();

27. 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

28. Comments • Line comment: // // my comment • Block comment: /* …… */ /* comment 1 Comment 2 … Comment n */