C# Introduction
ISYS 350
Visual Studio 2015 Demo
• Start page: New project/ Open project/Recent projects
• Starting project:
• File/New Project/
– Visual C#
– Windows
» Windows form application
– Project name/Project folder
• Project windows:
– Form design view/Form code view
– Solution Explorer
• View/Solution Explorer
– ToolBox (visible while in form design view)
– 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
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TextBox
Label
Button
CheckBox
RadioButton
ListBox
ComboBox
PictureBox
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.
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
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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
Show Full Name
.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
Compute Sum
.Control properties
.Event: Click, MouseMove, Form Load, 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.
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());
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.
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
• Examples:
double mydouble=12.7, rate=0.07;
int Counter = 0;
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);
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
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*/
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();
Note: The result of an integer divided by an integer is integer. For
example, 7/2 is 3, not 3.5.
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.
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)
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();
Year
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%
Comments
• Line comment: //
// my comment
• Block comment: /* …… */
/* comment 1
Comment 2
…
Comment n */