Chapter 2 : Data Processing

Question 1

Describe TextBox control ( 5 )

Answer 1

1. Rectangular area
2. Can accept keyboard input from the user
3. Locates in the common control group of the toolbox
4. Default name is textBoxn( n = 1 , 2 , 3 … )
5. Double click to add it to the form

Question 2

What property does TextBox controls?

Answer 2

1. Text property which stores user inputs

• Only accepts string values
  textBox1.Text = “Hello”;

Clear TextBox control content
textBox1.Text=””

Question 3

How to declare variable in C#?

Answer 3

1. DataType VariableName;

String text
double currency_rate

• Variable is a storage location in memory

Question 4

What are the bytes used in int, float and double?

Answer 4

1. int - 4 bytes
2. float - 4 bytes
3. double - 8 bytes

Question 5

What is char used for?

Answer 5

1. Storing a single character

• String is a collection of character

Question 6

What is most data type known as?

Answer 6

1. Primitive data types

Question 7

Ways to use variables ( 3 )

Answer 7

1. Store value
   product = “Mac Book”
2. Assign to another value
   productLabel.Text = product
3. Display in a message box
   MessageBox/.Show(product)

Question 8

What does a local variable belongs to?

Answer 8

1. Method which it was declared

• Only statements inside that method can access the variable

Question 9

What is the lifetime of a variable?

Answer 9

1. Time period during which the variable exists in memory while the program is executing

Question 10

List out the rules of variables ( 4 )

Answer 10

1. Can assign a value only if the value is compatible with the variable’s data type
2. A variable holds one value at a time
3. Variable must be assigned before it can be used, I can initialize the variable with a value when declare it
4. Multiple variables with the same type may be declared with one statement

Question 11

Can the value of int and double surrounded by quotes?

Answer 11

1. no

Question 12

What does the decimal data type indicates?

Answer 12

1. 128 bit data type

Question 13

What is the advantages of decimal compared to double

Answer 13

1. Makes appropriate for financial and monetary calculation since it has more precision and smaller range

Question 14

How to declare decimal data type?

Answer 14

1. decimal payRate = 28.5m
2. decimal price = 8.95M

• Need to add the letter M ( or m ) to a decimal value

Question 15

How to type casting?

Answer 15

1. Use a cast operator with parentheses with the type keyword
   ( type )

wholeNumber = ( int ) moneynumber

Question 16

List out arithmetic calculation ( 5 )

Answer 16

1. • , Add 2 numbers
2. • , Subtracts one number from another
3. • , Multiplies one number by another
4. / , Divides one number by another and gives the quotient
5. % , Divides one number by another and gives the remainder

Question 17

List out the result of mixed data type ( 3 )

Answer 17

1. When an operation involves an int and a double, int is treated as double and the result is double
2. When an operation involves an int and a decimal, it is treated as decimal and the result is decimal
3. An operation involving a double and decimal isn’t allowed

Question 18

What are the types of input collected from the keyboard?

Answer 18

1. Combinations of characters
   ( String Literals )

Question 19

How to let string literals input from keyboard to convert string into numeric data types?

Answer 19

1. int.Parse
2. double.Parse
3. decimal.Parse

Question 20

How to show numeric values in lablel?

Answer 20

1. Using ToString method

Question 21

List out format strings for the ToString method

Answer 21

1.”N” or “n”
- Number Format
- 12.3 ToString (“n3”) = 12.300
2. “F” or “f”
- Fixed-point Scientific Format
- 123456.0 ToString(“f2”) = 123456.00
3. “E” or “e”
- Exponential Scientific Format
- 123456.0 ToString(“e3”) = 1.235e + 005
4. “C” or “c”
- Currency Format
- -1234567.8 ToString(“C”) = ( $1,234,567.80 )
5. “P” or “p”
- Percentage Format
- .234 ToString(“P”) = 23.40%

Question 22

What is an exception?

Answer 22

1. An exception is an unexpected error that happens while a program is running

Question 23

What will happen if an exception isn’t handled by the program?

Answer 23

1. The program will abruptly halt

Question 24

List out the codes for exception handling

Answer 24

try{
}
catch {
}

• The catch block will execute when there is exception in the try block

Question 25

What is the constant value?

Answer 25

1. A constant is a name that represents a value that cannot be changed during the program’s execution

Question 26

How to declare constant variable in C#?

Answer 26

1. const double interest_rate = 0.129

Question 27

What is a field? ( 2 )

Answer 27

1. A variable that is declared at the class level
2. It is declared inside the class, not inside the method

Question 28

What is the scope of the field variable?

Answer 28

1. Entire class

public partial class Form1 : Form
{
// Declare a private field to hold a name.
private string name = “Charles”;
public Form1()
{
InitializeComponent();
}
private void showNameButton_Click(object sender, EventArgs e)
{
MessageBox.Show(name);
}
private void chrisButton_Click(object sender, EventArgs e)
{
name = “Chris”;
}

Question 29

List out 2 predefind constants and 2 complex mathematical calculations

Answer 29

1. Mathematical Calculations
   
   • Math.Sqrt(x)
   • Math.Pow( x , y )
2. Predefined Constants
   
   • Math.PI
   • Math.E

Question 30

How to create keyboard access key to buttons

Answer 30

1. Create a button ( Exit )
2. Add & before a letter ( E&xit )
3. Go to the Form ( Set Quit to the button )
4. User press Alt + E ( Quit the program )

Question 31

List out 2 properties to set up Colors

Answer 31

1. BackColor ( Background Color )
2. ForeColor ( Foreground Color )

Question 32

List out the 3 tabs for choosing color

Answer 32

1. Custom
   
   • Color palette
2. Web
   
   • Colors displayed consistently with Web Browser
3. System
   
   • List color defined in current Windows

Question 33

How to add background image to a form?

Answer 33

1. Use the BackgroundImage property in a Form

Question 34

List out property values for BackgroundImageLayour property

Answer 34

1. None
2. Title ( Repeat the image until it convers the screen width and height )
3. Center
4. Stretch
5. Zoom

Question 35

What is a GroupBox & Container?

Answer 35

1. \GroupBox is a container with a thin border and an optional title that can hold other controls
2. Container is a container that can hold other controls

Question 36

What is the difference between Panel & GroupBox

Answer 36

1. A panel cannot display a title and text while GroupBox can
2. A panel border can be specified byt its BorderStyle property