1. Data Types and Expressions2
C# Programming: From Problem Analysis to Program Design
4th Edition
C# Programming: From Problem Analysis to Program Design

2. Chapter Objectives Examine how computers represent data
Declare memory locations for data
Explore the relationship between classes, objects, and types
Use predefined data types
Use integral data types
C# Programming: From Problem Analysis to Program Design

3. Chapter Objectives (continued)
Use floating-point types
Learn about the decimal data type
Declare Boolean variables
Declare and manipulate strings
Work with constants
C# Programming: From Problem Analysis to Program Design

4. Chapter Objectives (continued)
Write assignment statements using arithmetic operators
Learn about the order of operations
Learn special formatting rules for currency
Work through a programming example that illustrates the chapter’s concepts
C# Programming: From Problem Analysis to Program Design

5. Data Representation Bits Bytes Bit – "Binary digIT"
Binary digit can hold 0 or 1
1 and 0 correspond to on and off, respectively
Bytes
Combination of 8 bits
Represent one character, such as the letter A
To represent data, computers use the base-2 number system, or binary number system
0/1 1 2 3 4 5 6 7
C# Programming: From Problem Analysis to Program Design

6. Bits and Bytes Nibble - 4 bits (half a byte) Byte - 8 bits
A group of 8 bits is called a byte.
Other groupings include:
Nibble - 4 bits (half a byte)
Byte - 8 bits
Kilobyte (KB) bytes (or 1024 x 8 bits)
Megabyte (MB) kilobytes (or bytes)
Gigabyte (GB) megabytes
Terabyte (TB) gigabytes
Most computers can process millions of bits every second.
A hard drive's storage capacity is measured in gigabytes or terabytes.
RAM is often measured in megabytes or gigabytes.

7. Decimal Number System
Figure 2-1 Base-10 positional notation of 1326

8. Decimal Number System 6 5 4 3 2 1
106
105
104
103
102
101
100 1M
100K
10K
1000 10
200,000 +
3000 +
400 +
60 +
5 =
203,465
Figure 2-1 Base-10 positional notation of 203,465

9. Data Representation (continued)
Table 2-1
Binary
equivalent
of selected
decimal
values
C# Programming: From Problem Analysis to Program Design

10. Binary Number System (continued)
Figure 2-2 Decimal equivalent of

11. Binary Number System 27 26 25 24 23 22 21 20 7 6 5 4 3 2 1 32 + 4 = 3627 26 25 24 23 22 21 20
128 64 32 16 8
= 36
Figure 2-1 Base-10 positional notation of 36

12. Binary Number System 7 6 5 4 3 2 1 27 26 25 24 23 22 21 20
128 64 32 16 8
= 161
Figure 2-1 Base-10 positional notation of 161

13. Data Representation (continued)
Character sets
With only 8 bits, can represent 28, or 256, different decimal values ranging from 0 to 255; this is 256 different characters
Unicode – character set used by C#.NET
Uses 16 bits to represent characters
216, or 65,536 unique characters, can be represented
Example: Euro '€' is '\u20AC'
Visit /charts
American Standard Code for Information Interchange (ASCII) – subset of Unicode
First 128 characters are the same

14. Data Representation (continued)
ASCII Table

15. Data Representation (continued)
List of Unicode characters
From Wikipedia, the free encyclopedia
"This article contains special characters. Without proper rendering support, you may see question marks, boxes, or other symbols.
This is a list of Unicode characters. As of version 10.0, Unicode contains a repertoire of over 136,000 characters covering 139 modern and historic scripts, as well as multiple symbol sets. As it is not technically possible to list all of these characters in a single Wikipedia page …"
Link:

16. Data Representation (continued)
List of Unicode characters
Link:
Console.WriteLine('\u00D1');

17. Data Representation (continued)
Table 2-2 Common abbreviations for data representations

18. Memory Locations for Data
Identifier
Name (camel notation)
Rules for creating an identifier
Combination of alphabetic characters (a-z and A-Z), numeric digits (0-9), and the underscore
First character in the name may not be numeric
No embedded spaces – concatenate (append) words together
Keywords cannot be used
Use the case of the character to your advantage
Be descriptive with meaningful names
Examples: customerName, productCode, addressLine1, savingAccountBalance

19. Reserved Words in C#
Table 2-3
C# keywords &
reserved words

20. Contextual Keywords Table 2-4 C# contextual keywords
Never use these words as variable names – It is a very bad idea!!!

21. Naming Conventions Pascal case Camel case
First letter of each word capitalized
Class, method, namespace, and properties identifiers
Eg: FirstName, LastName
Camel case
Hungarian notation
First letter of identifier lowercase; first letter of subsequent concatenated words capitalized
Variables and objects
Eg: firstName, lastName, savingAccountBalance

22. Examples of Valid Names (Identifiers)
Table 2-5 Valid identifiers

23. Examples of Invalid Names (Identifiers)
Table Invalid identifier

24. Variables
Area in computer memory where a value of a particular data type can be stored
Declare a variable
Allocate memory
Syntax
type identifier;
Compile-time initialization
Initialize a variable when it is declared
type identifier = expression;

25. Types, Classes, and Objects
C# has more than one type of number
int type is a whole number
Floating-point types can have a fractional portion
Types are actually implemented through classes
One-to-one correspondence between a class and a type
Simple data type such as int, string, … implemented as classes
C# Programming: From Problem Analysis to Program Design

26. Type, Class, and Object Examples
Table 2-7 Sample data types
C# Programming: From Problem Analysis to Program Design

27. Predefined Data Types Common Type System (CTS)
Divided into two major categories
Figure NET common types

28. Value and Reference Types
Figure 2-4 Memory representation for value and reference types

29. Value Types Fundamental or primitive data types
Figure 2-5 Value type hierarchy

30. Value Types Figure 2-5 Type Examples Integral: 123
Floating point: 1.57e+3 (same as 1570)
Decimal: 1.23
Boolean true / false
Struct class Person…{name, age, sex…}
Enumerated enum Days { Sunday, Monday, Tuesday,
Wednesday, Thursday, Friday, Saturday };
enum Months : byte { Jan, Feb, Mar, Apr,
May, Jun, Jul, Aug, Sep, Oct, Nov, Dec };
Figure 2-5 Type Examples

31. Value Types (continued)
Table 2-8
C# value
data types with
.NET alias

32. Integral Data Types Includes number of types Primary difference
How much storage is needed
Whether a negative value can be stored
Includes number of types
byte & sbyte
char
int & uint
long & ulong
short & ushort

33. Data Types
Table 2-9 Values and sizes for integral types

34. Examples of Integral Variable Declarations
int studentCount; // number of students in the class
int ageOfStudent = 20; // age-originally initialized to 20
int numberOfExams; // number of exams
int coursesEnrolled; // number of courses enrolled

35. Table 2-10 Values and sizes for floating-point types
May be in scientific notation with an exponent
Format is: n.ne±P
3.2e+5 is equivalent to 320,000
1.76e-3 is equivalent to
OR in standard decimal notation
Default type is double
Table Values and sizes for floating-point types

36. Examples of Floating-Point Declarations
double extraPerson = 3.50; // extraPerson originally set
// to 3.50
double averageScore = 70.0; // averageScore originally set
// to 70.0
double priceOfTicket; // cost of a movie ticket
double gradePointAverage; // grade point average
float totalAmount = 23.57f; // note the f must be placed after
// the value for float types

37. Table 2-11 Value and size for decimal data type
Decimal Types
Monetary data items
As with the float, must attach the suffix ‘m’ or ‘M’ onto the end of a number to indicate decimal
Float attach ‘f’ or ‘F’
Table Value and size for decimal data type
Examples
decimal endowmentAmount = M;
decimal deficit;

38. Boolean Variables Based on true/false, on/off logic
Boolean type in C# → bool
Does not accept integer values such as 0, 1, or -1
Default value is: false
bool undergraduateStudent;
bool moreData = true;

39. Strings Reference type Represents a string of Unicode characters
string studentName;
string courseName = "Programming I";
string twoLines = "Line1\nLine2";

40. Making Data Constant Add the keyword const to a declaration
Value cannot be changed
ALLCAPS standard naming convention
Syntax: const type identifier = expression;
const double TAX_RATE = ;
const int SPEED = 70;
const char HIGHEST_GRADE = 'A';

41. Assignment Statements
Used to change the value of the variable
Assignment operator ( = )
Syntax
variable = expression;
Expression can be:
Another variable
Compatible literal value
Mathematical equation
Call to a method that returns a compatible value
Combination of one or more items in this list

42. Examples of Assignment Statements
int numberOfMinutes,
count,
minIntValue;
numberOfMinutes = 45;
count = 0;
minIntValue = ;
count = count + 1;
numberOfMinutes = 10 + Delay(clerkId);

43. Examples of Assignment Statements
char firstInitial,
yearInSchool,
punctuation,
enterKey,
lastChar;
firstInitial = 'B';
yearInSchool = '1';
punctuation = ';';
enterKey = '\n'; // newline escape character
lastChar = '\u005A'; // Unicode character 'Z'
euroSymbol= '\u20AC'; // Unicode character '€'

44. Examples of Assignment Statements (continued)
double accountBalance,
weight;
bool isFinished;
accountBalance = ;
weight = 1.7E-3; //scientific notation may be used
isFinished = false; //declared previously as a bool
//Notice – no quotes used

45. Examples of Assignment Statements (continued)
decimal amountOwed,
deficitValue;
amountOwed = m; // m or M must be suffixed to
// decimal data types
deficitValue = M;

46. Examples of Assignment Statements (continued)
string aSaying, fileLocation;
aSaying = "First day of the rest of your life!\n";
fileLocation "C:\textFiles\newChapter2";
@ placed before a string literal signals that the characters
inside the double quotation marks should be interpreted verbatim --- No need to use escape characters

47. Examples of Assignment Statements (continued)
Figure 2-7 Impact of assignment statement

48. Arithmetic Operations
Simplest form of an assignment statement
resultVariable = operand1 operator operand2;
Readability
Space before and after every operator
Table Basic arithmetic operators

49. Basic Arithmetic Operations
Figure 2-8 Result of 67 % 3
Modulus operator with negative values
Sign of the dividend determines the result
-3 % 5 = -3; % -3 = 2; % -3 = -3;

50. Basic Arithmetic Operations (continued)
Plus (+) with string Identifiers
Concatenates operand2 onto end of operand1
string result;
string fullName;
string firstName = "Daenerys";
string lastName = "Targaryen";
fullName = firstName + " " + lastName;
//now fullName is "Daenerys Targaryen"

51. Concatenation
Figure 2-9 String concatenation

52. Basic Arithmetic Operations (continued)
Increment and Decrement Operations
Unary operator
num++; // num = num + 1;
--value1; // value = value – 1;
Preincrement/predecrement versus post
int num = 100;
Console.WriteLine(num++); // Displays 100
Console.WriteLine(num); // Displays 101
Console.WriteLine(++num); // Displays 102

53. Basic Arithmetic Operations (continued)
Figure Declaration of value type variables

54. Basic Arithmetic Operations (continued)
Figure Change in memory after count++; statement executed

55. Basic Arithmetic Operations (continued)
int num = 100;
Console.WriteLine(num++); //prints 100
Console.WriteLine(num); //prints 101
Console.WriteLine(++num); //prints 102
C# Programming: From Problem Analysis to Program Design

56. Basic Arithmetic Operations (continued)
Figure Results after statement is executed

57. Compound Operations Accumulation
Variable on left side of equal symbol is used once the entire expression on right is evaluated

58. Basic Arithmetic Operations (continued)
Order of operations
Order in which the calculations are performed
Example
answer = 100;
answer += 50 * 3 / 25 – 4;
50 * 3 = 150
150 / 25 = 6
6 – 4 = 2
= 102

59. Order of Operations Associativity of operators Left Right
Table Operator precedence
Associativity of operators
Left
Right
NOTE. When an operator has right associativity, its expression is evaluated from right to left. For example, the assignment operator is right-associative. Therefore, the expression to its right  is evaluated before the assignment operation is invoked. 

60. Order of Operations (continued)
Figure Order of execution of the operators

61. Mixed Expressions Implicit type coercion
Changes int data type into a double
No implicit conversion from double to int
double answer;
answer = 10 / 3; // Does not produce
double answer2;
answer2 = 10.0 / 3; // produces
int value1 = 440,
anotherNumber = 70;
double value2 = ;
value2 = value1; // ok, stored in value2

62. Figure 2-14 Syntax error generated for assigning a double to an int
Mixed Expressions
int value1 = 440;
double value2 = ;
value1 = value2; // syntax error as shown in Figure 2-14
Figure Syntax error generated for assigning a double to an int

63. Mixed Expressions (continued)
Explicit type coercion
Cast
(type) expression
examAverage = (exam1 + exam2 + exam3) / (double) count;
int value1 = 0,
anotherNumber = 75;
double value2 = ,
anotherDouble = 100;
value1 = (int) value2; // value1 = 100
value2 = (double) anotherNumber; // value2 = 75.0

64. Mixed Expressions (continued)
Explicit Conversion ( Using the Convert class )
int v1 = Convert.ToInt32(1.999); // v1 is 1
long v2 = Convert.ToInt64("5.7777"); // v2 is
string v3 = Convert.ToString(1.999); // v3 is "1.999"
char v4 = Convert.ToChar(65); // v4 is 'A'

65. Formatting Output
You can format data by adding dollar signs, percent symbols, and/or commas to separate digits
You can suppress leading zeros
You can pad a value with special characters
Place characters to the left or right of the significant digits
Use format specifiers

66. Formatting Output (continued)
Table Examples using format specifiers

67. Numeric Format Specifiers
Table Standard numeric format specifiers

68. Numeric Format Specifiers (continued)
Table Standard numeric format specifiers (continued)

69. Custom Numeric Format Specifiers
Table Custom numeric format specifiers

70. Custom Numeric Format Specifiers (continued)

71. Width Specifier
Useful when you want to control the alignment of items on multiple lines
Alignment component goes after the index ordinal followed by a comma (before the colon)
If alignment number is less than actual size, it is ignored
If alignment number is greater, pads with white space
Negative alignment component places spaces on right
Console.WriteLine("{0,10:F0}{1,8:C}", 9, 14);
9 $ //Right justified values

72. Interpolated Strings (New in C# 6)
The $ special character identifies a string literal as an interpolated string.
An interpolated string looks like a template string that contains expressions to be replaced by the string representations of their results.
This style offers a readable and convenient way to create formatted strings.
string name = "Diana Prince";
DateTime date = DateTime.Now;
// Composite formatting:
Console.WriteLine("Hello, {0}! Today is {1}, it's {2:HH:mm} now.", name, date.DayOfWeek, date);
// String interpolation:
Console.WriteLine($"Hello, {name}! Today is {date.DayOfWeek}, it's " +
$"{date:HH:mm} now.");
// in both cases the output is
// Hello, Diana Prince! Today is Sunday, it's 15:20 now.

73. Programming Example – CarpetCalculator
Figure Problem specification sheet for the CarpetCalculator example

74. Data Needs for the CarpetCalculator
Table Variables

75. Nonchanging Definitions for the CarpetCalculator
Side Note: 1 yard = 3 feet
1 sqy = 9 sqf
Table Constants

76. CarpetCalculator Example
Figure Prototype for the CarpetCalculator example

77. Algorithm for CarpetCalculator Example
Figure CarpetCalculator flowchart

78. Algorithm for the CarpetCalculator Example (continued)
Figure Structured English for the CarpetCalculator example

79. CarpetCalculator Example (continued)
Figure Class diagram for the CarpetCalculator example

80. CarpetCalculator Example (continued)
Figure Revised class diagram without methods

81. /* CarpetCalculator.cs Author: Doyle*/
using System;
namespace CarpetExample {
class CarpetCalculator
static void Main( )
const int SQ_FT_PER_SQ_YARD = 9;
const int INCHES_PER_FOOT = 12;
const string BEST_CARPET = "Berber";
const string ECONOMY_CARPET = "Pile";
int roomLengthFeet = 12, roomLengthInches = 2,
roomWidthFeet = 14, roomWidthInches = 7;
double roomLength, roomWidth, carpetPrice,
numOfSquareFeet,
numOfSquareYards,
totalCost;

82. roomLength = roomLengthFeet +
(double) roomLengthInches / INCHES_PER_FOOT;
roomWidth = roomWidthFeet +
(double) roomWidthInches / INCHES_PER_FOOT;
numOfSquareFeet = roomLength * roomWidth;
numOfSquareYards = numOfSquareFeet / SQ_FT_PER_SQ_YARD;
carpetPrice = 27.95; //per square yard
totalCost = numOfSquareYards * carpetPrice;
Console.WriteLine("The cost of " + BEST_CARPET
+ " is {0:C}", totalCost);
Console.WriteLine( );
carpetPrice = 15.95; //per square yard
Console.WriteLine("The cost of " + ECONOMY_CARPET
+ " is " + "{0:C}", totalCost);
Console.Read(); }

83. Coding Standards Naming conventions Spacing conventions
Identifiers
Spacing conventions
Declaration conventions
C# Programming: From Problem Analysis to Program Design

84. Resources Naming Guidelines for .NET –
Writing Readable Code –
C# Video tutorials –
Visual Studio 2012 – C# –

85. Chapter Summary Memory representation of data Bits versus bytes
Number system
Binary number system
Character sets
Unicode
C# Programming: From Problem Analysis to Program Design

86. Chapter Summary (continued)
Memory locations for data
Relationship between classes, objects, and types
Predefined data types
Integral data types
Floating-point types
Decimal type
Boolean variables
Strings
C# Programming: From Problem Analysis to Program Design

87. Chapter Summary (continued)
Constants
Assignment statements
Order of operations
Formatting output
C# Programming: From Problem Analysis to Program Design

88. Appendix 1 Formatting Numbers
using System;
using System.Globalization;
using System.Resources;
using System.Threading;
class Sample {
public static void Main()
Console.WriteLine(String.Format("{0:0.00}", )); //
Console.WriteLine(String.Format("{0:0.00}", 1.2)); // 1.20
Console.WriteLine(String.Format("{0:0.00}", 0.1)); // 0.10
Console.WriteLine(String.Format("{0:0.00}", 123.0)); //
Console.WriteLine(String.Format("{0:0.00}", 123)); //
Console.WriteLine(String.Format("{0:00.0}", ) ); // 123.5
Console.WriteLine(String.Format("{0:00.0}", 1.99) ); // 02.0
Console.WriteLine(String.Format("{0:0,0.0}", )); // 12,345.7
Console.WriteLine(String.Format("{0:#.00}", 0.1) ); // .10
Console.WriteLine(String.Format("{0,10:0.0}", )); // _____123.5
Console.WriteLine(String.Format("{0,-10:0.0}", )); // 123.5____
Console.WriteLine(String.Format("Balance is ${0,-10:0.0}USD", )); // Balance is $123.5____USD
Console.WriteLine(String.Format("{0:Balance is $0.0 USD}", )); // Balance is $123.5____USD
Console.WriteLine(String.Format("{0:00000}", 123) ); // 00123
Console.WriteLine(String.Format("{0,5}", 123) ); // __123
Console.WriteLine(String.Format("{0,-5}", 123)); // 123__
Console.WriteLine(String.Format("{0:(###) ###-####}", )); // (216)
Console.WriteLine(String.Format("{0:(000) }", )); // (216)
double decNum = 1.23;
string strUSA = decNum.ToString(CultureInfo.InvariantCulture.NumberFormat); // "1.23"
string strEurope = decNum.ToString(CultureInfo.GetCultureInfo("es-ES").NumberFormat); // "1,23"
Console.WriteLine(strUSA ); // "1.23"
Console.WriteLine(strEurope ); // "1,23"
Console.ReadKey(); }

89. Appendix 2 Formatting Dates
using System;
using System.Globalization;
using System.Resources;
using System.Threading;
class DemoFormatDates {
public static void Main()
//using other Culture values. See Link: //
//Thread.CurrentThread.CurrentCulture = new CultureInfo("es-VE");
//Thread.CurrentThread.CurrentCulture = new CultureInfo("en-UK");
//Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
//Thread.CurrentThread.CurrentCulture = new CultureInfo("el-GR");
CultureInfo ci = Thread.CurrentThread.CurrentCulture;
Console.WriteLine(ci); // en-US
DateTime dt = DateTime.Now;
Console.WriteLine(dt); // 8 / 8 / :39:58 PM
Console.WriteLine(String.Format("{0:y yy yyy yyyy}", dt)); //
Console.WriteLine(String.Format("{0:M MM MMM MMMM}", dt)); // Aug August
Console.WriteLine(String.Format("{0:d dd ddd dddd}", dt)); // Sat Saturday
Console.WriteLine(String.Format("{0:h hh H HH}", dt)); // hour 12/24
Console.WriteLine(String.Format("{0:m mm}", dt)); // minutes
Console.WriteLine(String.Format("{0:s ss}", dt)); // seconds
Console.WriteLine(String.Format("{0:t tt}", dt)); // P PM A.M. or P.M.
Console.WriteLine(String.Format("{0:z zz zzz}", dt)); // : time zone
Console.ReadKey(); }
C# Programming: From Problem Analysis to Program Design

90. Appendix 3 Formatting Dates
using System;
using System.Globalization;
using System.Resources;
using System.Threading;
class Sample {
public static void Main()
DateTime dt = DateTime.Now;
Console.WriteLine(dt); // 8 / 8 / :22:15 PM
Console.WriteLine(String.Format("{0:t}", dt)); // 10:22 PM ShortTime
Console.WriteLine(String.Format("{0:T}", dt)); // 10:22:15 PM LongTime
Console.WriteLine(String.Format("{0:d}", dt)); // 8 / 8 / ShortDate
Console.WriteLine(String.Format("{0:D}", dt)); // Saturday, August 08, LongDate
Console.WriteLine(String.Format("{0:F}", dt)); // Saturday, August 08, :22:15 PM FullDateTime
Console.WriteLine(String.Format("{0:r}", dt)); // Sat, 08 Aug :22:15 GMT RFC1123
Console.WriteLine(String.Format("{0:u}", dt)); // :22:15Z UniversalSortableDate
Console.ReadKey(); }
C# Programming: From Problem Analysis to Program Design

91. Appendix 4 Formatting Tables
using System;
using System.Globalization;
using System.Resources;
using System.Threading;
class Sample {
public static void Main()
Console.WriteLine("First Name| Last Name | Age ");
Console.WriteLine(" ===============+-----");
Console.WriteLine(String.Format("{0,-10}|{1,-15}|{2,5}", "Daenerys", "Targaryen", 19));
Console.WriteLine(String.Format("{0,-10}|{1,-15}|{2,5}", "Drogon", "", 3));
Console.WriteLine(String.Format("{0,-10}|{1,-15}|{2,5}", "Maester", "Aemon", 102));
Console.ReadKey(); }