Starting Out in C# - Chapter 3 Questions
order of operations
PEMDAS
summarize the mathematical order of operations
PEMDAS
panel control
Panel control is like a group box but does not have a tile, text property and the border style can be changed.
In code, how do you retrieve data that has been typed into the TextBoxControl?
Retrieving the contents of the control's Text property.
What kind of code does the try block of a try-catch statement contain?
Statements that could potentially throw an exception
What type of data does a control's Text property always contain?
String
What control can be used to gather text input from the user?
TextBox Control
What access modifier should you use when declaring a field? why?
private field because in prevents code from outside the class from changing the values of a class's field preventing bugs
Will the following cause an error, why or why not? string luckyNumber = 7;
yes because it defines the data type of string but does not include the number 7 in double quotes to make it a string.
exception object
a variable created in memory when an exception is thrown that stores data about the exception
field
a variable declared in a class instead of an individual method
try-catch statement
A type of exception handler which has the program "try" a group of arguments, and if they fail, ''catch" the failure.
what value with the wholePieces variable contain after the following code executes? double totalPieces = 6.5; int wholePieces = (int)totalPieces;
6
assume the result is an int variable. When the following statement executes, what value will be stored in result? result = (2 + 5) * 10;
70
Assume the result is a double variable. When the following statement executes what value will be stored in result? result = 4 + 10 / 2;
9
parse
A family of methods in the .NET Framework which means to analyze a string of character for some purpose.
what value will be displayed in the message box when the following code segment is executed? double apples = 12.0; MessageBox.Show (apples.ToString("N0"));
12
assume result is a double variable. When the following statement executes what value will be stored in result? result = 5/2;
2.5
access key
Also known as a mneumonic; a key that is pressed in combination with the Alt key to access quickly a control such as a button
Assuming the variable greeting has not been assigned a value, what will be the result of the following statement MessageBox.Show(greeting);
An error
exception
An unexpected error that occurs while a program is running, causing the program to halt.
How can you display the default error message when an exception is thrown?
Assign name to the exception object when writing the catch clause of a try-catch statement and then use the Message property of the exception object in the catch block to display the default error message in a message box
How do you get out of break mode when an exception is thrown?
Click Stop debugging button or pressing Shift + F5
primitive data types
Data types which hold fundamental types of data such as strings, integers and real numbers
What is the lifetime of a variable that is declared inside of a click event handler
From the click to when the code concludes
List the operands for the following math expression. length * width
Length, Width
what method of the math class can be used to determine larger of two values?
Math.Max
what method of the Math class can be used to determine the smaller of two values?
Math.Min
Write a programming statement that displays the string value of a variable named salary in a message box using currency format.
Messagebox.Show(salary.ToString("c"));
math operators
The item that defines what to do with values in a math expression (+, -, =, etc)
What are two advantages of using named constants?
They make the program more self-explanatory and allow for widespread changes to easily be made to the program.
What is the purpose of a variable?
To store a value in memory
cancel button
a button on a form that is automatically clicked when the user presses the escape key
constant field
a field that cannot be changed by any statement in the class. exception will occur if a statement attempts to change a constant field.
How is the lifetime of a field different from the lifetime of a local variable?
a local variable exists only while the method in which it is declared is executing but a field exists as long as the form exists.
numeric literal
a number written into the programs code.
argument
a piece of data passed into a method
TextBox control
a rectangular area on a form that when the application is running, the user can type text into it. The program can then retrieve the text that the user entered and use it in any necessary operations.
break mode
a special window which appears when an exception occurs and displays which line of code caused the error.
variable
a storage location in memory that is represented by a name.
Write a statement that displays each of the following numeric variables in a message box a. grandTotal b. highScore c. sum d. width
a. Messagebox.Show(grandtotal.ToString( )); b. Messagebox.Show(highScore.ToString( )); c. Messagebox.Show(sum.ToString( )); d. Messagebox.Show(width.ToString( ));
Rewrite the following statements using combined assignment operators: a. count = count + 1; b. amount = amount - 5; c. radius = radius * 10; d. length = length / 2;
a. count =+ 1; b. amount =- 5; c. radius =* 10; d. length =/ 2;
specify the appropriate primitive numeric data type for each of the following values. a. 24 dollars b. 12 bananas c. 14.5 inches d. 83 cents e. 2 concert tickets
a. decimal b. int c. double d. decimal e. int
write a statement that converts each of the following string values to the decimal data type using the decimal.parse method. a. "9.05" b. grandTotal c. "50" d. priceTextBox.Tex
a. decimal.parse("9.05"); b. decimal.parse(grandTotal); c. decimal.parse("50"); d. decimal.parse(priceTextbox.Text);
for each of the following items, determine whether the data type should be an integer, string, or real number. a. Pet name b. Sales Tax c. Mailing Address d. Video Game Score
a. string b. real number c. string d. integer
Indicate whether each of the following is a legal variable name. if not, why? a. pay_Rate b. speed of sound c. totalcost d. 2ndPlaceName
a. yes b. no spaces are not allowed c. yes d. no, a number cannot start a variable name
ForeColor
allows you to change the color of the text.
BackColor property
allows you to change the objects background color
ToString Method
allows you to convert variables to string values
What can cause an application to throw an exception?
an unexpected error while the program is running, such as user input that is not in the correct format
where should you place field declarations in a program?
at the top of a class declaration, before any methods
Which of the following will cause an error, why? a. decimal payRate = 24m; b. int player score = 1240.5; c. double box width 205.25; d. string lastName = "Holm";
b. because variables of the int data type can be assigned only whole-number values.
local variable
belongs to the method in which it is declared and only statements inside that method can access the variable.
accept button
button on a form that is automatically clicked when a user presses the enter key
How do you clear the contents of a Textbox Control?
by assigning the string " " to the TextBox
catch block
catch followed by a group of one or more statements enclosed by brackets
exception handler
code that responds to exceptions when they're thrown and prevents the program from crashing
focus method
code to move the focus from one object to another
concatenation
common operation performed on string adding one string to the end of another using the + operator.
Write a programming statement that declares a named constant for a 10 percent discount.
const double DISCOUNT = 0.1;
TabIndex property
contains a numeric value which indicates a control's position in the tab order
decimal.parse method
converts a string into a decimal
double.parse method
converts a string into a double
int.Parse method
converts string into an integer
Rewrite the following code segment so that it does not cause an error. decimal pricePerFoot = 2.99m; double boardLength = 10.5; decimal total cost = boardLength * pricePerFoot
decimal pricePerFoot = 2.99m; double boardLength = 10.5; decimal total cost = (decimal)boardLength * pricePerFoot;
tab order
defines in which order controls receive focus
combined assignment operators
designed specifically for common operations used in programing.
write a programming statement that uses the math.Pow method to square the number 12 and store the result in a double variable named product.
double product = Math.Pow(12.0, 2.0);
initialize
give variable a string
What will be stored in the message variable after the following statement is executed ? string message = "he" + "ll" + "o!";
hello
variable name
identifies the variable in the code.
What causes the program to jump to the catch clause and execute the catch block of a try-catch statement?
if a statement in the try block throws an exception
formatting string
indicates how you want a number to appear, formatted in a specific way. (using N & C for example)
write a programming statement that will convert the following decimal variable to an int and store the result in an int variable named dollars: decimal deposit = 976.54m;
int dollars = (int)deposit;
What method converts the string literal "40" to a value of the int data type?
int.Parse
Write a programming statement that uses the ToString Method of a variable named millimeters so that it displays a precision of four digits after the decimal point in fixed-point scientific format.
millimeters.ToString("f4");
tab order selection mode
mode to change and define the tab order of a form.
Write a programming statement that gives the focus to a TextBox control named numberTextBox
numberTextBox.Focus( );
decimal literal
numeric literal treated as a decimal.
double literal
numeric literal treated as a double
integer literal
numeric literal treated as an integer
catch clause
one or more statements enclosed in brackets defining what happens when an exception occurs
How do you display a form in tab order selection mode? How do you exit tab order selection mode?
open the tab order selection mode
math expression
performs a calculation and gives a value
Write a programming statement that declares a constant field for a 5.9 percent interest rate
private const decimal INTEREST_RATE = 0.059m;
GroupBox Control
rectangular control that appears with a thin border and optional title as a container to hold other controls.
write a statement that will store the value of an int variable named result in the Text property of a label control named resultLabel.
resultLabel.Text = result.ToString( );
access modifier
specifies how a class member can be accessed by code outside of the class
variable declaration
specifies the variables name and data type
Give an example of a variable declaration that will store the value of your favorite food.
string favoritefood = "Pizza";
Write a single declaration statement for the variables name, city and state
string name, city, State
What happens if you press the Enter key while a Button control has the focus?
the button's click event handler will execute
focus
the item that receives the user's keyboard input
scope
the part of a program in which a variable can be accessed.
truncation
the process of dropping a numbers fractional part
Suppose an application has a decimal variable named total and a label control named totalLabel what would be the result when the following assignment statement is executed? totalLabel.Text = total;
the result will be an error because numeric values cannot be assigned to strings.
lifetime
the time period during which the variable exists in memory while the program is executing. based on the scope of the variable.
data type
the type of data a variable will hold
operands
the values on the left and right of the operator (*, /, +, etc)
cast opperator
used to explicitly convert a value from one numeric data type to another, with the understanding that changing data types may result in a loss of data
