More Related Content
What's hot
What's hot (20)
Similar to Chapter 03
Similar to Chapter 03 (20)
More from Terry Yoast
More from Terry Yoast (20)
Recently uploaded
Recently uploaded (20)
Chapter 03
- 1. aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf aslkjdhfalskhjfgalsdkfhalskdhjfglaskdhjflaskdhjfglaksjdhflakshflaksdhjfglaksjhflaksjhf
- 2. Variables, Constants and Calculations Chapter 3 McGraw-Hill © 2006 The McGraw-Hill Companies, Inc. All rights reserved.
- 7. Data Types 4 Any type of data Object Varies Alphanumeric data: letters, digits, and other characters String 8 Larger whole numbers Long 4 Whole numbers in the range -2,147,483,648 to +2,147,483,647 Integer 2 Small integer in the range -32,768 to 32,767 Short 8 Double precision floating-point numbers with 14 digits of accuracy Double 4 Single precision floating-point numbers with six digits of accuracy Single 16 Decimal fractions, such as dollars/cents Decimal 8 1/1/0001 through 12/31/9999 Date 2 Single Unicode character Clear 1 0 to 255, binary data Byte 2 True or False value Boolean Storage Size in bytes Use For Data Type
- 12. Declaration Statement Examples As Decimal Private priceDecimal As Decimal Dim priceDecimal As Single Dim temperatureSingle As Integer Private totalSoldInteger As Integer As String Dim customerName Strging As String
- 14. Module Level Variable Declaration Example Code module-level declarations in the Declaration section at the top of the code
- 19. Conversion Examples quantityInteger =Integer.Parse(quantityTextBox.Text) priceDecimal =Decimal.Parse(priceTextBox.Text) wholeNumberInteger =Integer.Parse(digitString) resultLabel.Text =resultDecimal.ToString( ) countTextBox.Text =countInteger.ToString( ) idString =idInteger.ToString( )
- 31. Format Specifier Codes Percent P or p Digits D or d Number N or n Fixed-point F or f Currency C or c Name Format Specifier Codes
- 32. Format Specifier Code Examples ($10.00) "C" -10 valueInteger 8% "P0" 0.075 rateDecimal 7.500% "P3" 0.075 rateDecimal 7.50% "P" 0.075 rateDecimal 000123 "D6" 123 pinInteger 1,126 "N0" 1125.6744 totalDecimal $1,125.67 "C" 1125.6744 totalDecimal Output Code Value Variable
- 36. Try Block - General Form Try statements that may cause error Catch [VariableName As ExceptionType] statements for action when an exception occurs [ Finally statements that always execute before exit of Try block] End Try
- 37. Try Block - Example Catches Any Exception Try quantityInteger = Integer.Parse(quantityTextBox.Text) Me.quantityLabel.Text = quantityInteger.ToString( ) Catch Me.messageLabel.Text = "Error in input data." End Try
- 39. Common Exception Classes Each exception is an instance of the Exception class. The properties of this class allow you to determine the code location of the error, the type of error and cause.
- 40. Try Block - Example Handling Multiple Exceptions Try ' Statements that may cause errors. Catch theException As FormatException ' Statements for nonnumeric data. Catch theException As ArithmeticException ' Statements for calculation problem. Catch theException As Exception ' Statements for any other exception. End Try
Editor's Notes
- Brief description on how to navigate within this presentation (ppt) The first time a Key Term from the chapter is used in the ppt it will display in blue Gold colored text boxes display coding examples Slides will be numbered (# of #) when multiple slides on same topic (Slide title) Speaker notes are included where appropriate for slides (*)Denotes either a comment for page reference to textbook or slide reference in ppt
- When you declare a variable or a named constant, VB reserves an area of memory and assigns it a name, called an identifier Identifier names are specified according to the rules of Basic as well as some recommended naming conventions
- The data type of a variable or constant indicates what type of information will be stored in the allocated memory space The data type charts displays the kind of data each type of data types hold, and the amount of memory allocated for each
- A programmer has to name (identify) the variables and named constants that will be used in a project
- Constants provide a way to use words to describe a value that doesn’t change Constants are declared using the keyword and are given a name, a data type, and a value Once a value is declared as a constant, its value can’t be changed during the execution of the project Data type declared and data type of the value must match Many sets of intrinsic constants (key term) are declared in system class libraries and are available for use in VB programs
- If a type-declaration character is not appended any whole number is assumed to be Integer and any fractional value is assumed to be Double Use two quotes with a string literal to avoid confusion
- VB IntelliSense feature helps you enter Private, Public, and Dim statements—after you type the space that follows VariableName As, a list pops up and displays the possible entries for data type to complete the statement If you begin to complete the statement the list automatically scrolls to the correct section; when the correct entry is highlighted press Enter, Tab, or the spacebar to select the entry or double-click if using the mouse The reserve word Dim is really short dimension, which means size. When declaring a variable, the amount of memory reserved depends on its data type.
- A variable may exist and be visible for an entire project, for only one form, or for only one procedure Visibility really means “this variable can be used or ‘seen’ in this location.” Namespace - Available to all procedures of project Module - Available to all procedures within that module (often a form) Use Public or Private keywords Local - Available only to the procedure in which it is declared Block - Available only in block of code inside a procedure where declared An example of a module level variable declaration is displayed on the next slide (Slide 15)
- The class that you use depends on the data type of the variable to which you are assigning a value; for example, to convert text to an integer, use the Integer.Parse method
- When you assign a value to a variable, you must take care to assign like types; you assign an integer value to an Integer variable and a decimal value to a Decimal variable ( chart shown on next slide, Slide 19) There are some exception to the rule about assigning only like types See “Implicit Conversions”
- The arithmetic operations you can perform you can perform in VB include addition, subtraction, multiplication, division, integer division, modulus, and exponentiation The first four operations are self explanatory, but you may not be familiar with Integer Division, Modulus, and/or exponentiation Integer division-use to divide one integer by another giving an integer result truncating (dropping) any remainder Modulus – returns the remainder of a division problem Exponentiation – raises a number to the pwer specified and retruns (produces) a result of the Double data type
- VB provides two options that can significantly change the behavior of the editor and compiler Not using either Option Explicit and/or Option Strict can make coding somewhat easier but provide opportunities for hard-to-find errors and very sloppy programming When Option Explicit is turned off, programmers can use any variable name without first declaring it which is a throwback to the older version of Basic and programmers spent many hours debugging programs that had small typos in a variable name Programmers should always program with Option Explicit turned on-in VB.NET the option is turned on by default for all new projects. Programmers will need to place a an additional code line before the first line of code in a file to turn it off When Option Strict it turned on, the editor and compiler try to help keep programmers from making hard-to-find mistakes. By having Option Strict turned on programmers can be saved from developing poor programming habits
- In VB you can convert data from one numeric data type to another—some conversions can be performed implicitly (automatically) and some you must specify explicitly. *Refer to p. 114 for tables displaying Conversion examples
- The expression countInteger / 2* amount Decimal is evaluated as integer division for countInteger /2, producing an integer intermediate result; then the multiplication is performed on the integer and decimal value (amountDecimal), producing a decimal result
- See the Appendices for additional mathematical, financial and string functions
- When wanting to display numeric data in the Text property of a label or text box the value must first be converted to string—the data can be formatted which controls the way the output will look
- The format specifier codes formats the display of output and are predefined The default format of each of the formatting codes is based on the computer’s regional setting Format specifier codes are displayed on the next slide (Slide 32) and examples are shown on the following slide (Slide 33)
- The strings returned are based on the computer’s regional settings and can be changed. Currently the default values are set for US-English in Windows XP *Refer to chart on p. 118
- When users input numbers and use those numbers in calculations, lots of things can go wrong—for example, the Parse methods, Integer.Parse and Decimal.Parse fail if the user enters nonnumeric data or leaves the text box blank
- The Try-Block General Form is shown on the next slide (Slide 37)
- *Refer to the chart on p. 125 for Common Exception Classes examples
- If wanting to trap for more than one type of exception multiple Catch blocks (handlers) can be included. When an exception occurs, the Catch statements are checked in sequence.
- Two sample message boxes
- Programs often need to calculate the sum of numbers. The technique for summing is to declare a module-level variable for the total