Data Types and Expressions - csuohio.edugrail.cba.csuohio.edu/~matos/notes/ist-211/csNotes/9781285096261... · C# Programming: From Problem Analysis to Program Design 1 Data Types

C# Programming: From Problem Analysis to Program Design

1

Data Types

and

Expressions 2 C# Programming: From Problem Analysis to Program Design

4th Edition


2

Chapter Objectives


3

Chapter Objectives (continued)


4

Chapter Objectives (continued)


5

Data Representation

0/1

0 1 2 3 4 5 6 7

Bits and Bytes

6

7

Decimal Number System

Decimal Number System 6 5 4 3 2 1 0

106 105 104 103 102 101 100

1M 100K 10K 1000 100 10 1

0 2 0 3 4 6 5

200,000 + 3000 + 400 + 60 + 5 = 203,465


9

Data Representation (continued)

Table 2-1

Binary

equivalent

of selected

decimal

values

10

Binary Number System

(continued)

Figure 2-2 Decimal equivalent of 01101001

11


Figure 2-1 Base-10 positional notation of 36

7 6 5 4 3 2 1 0

27 26 25 24 23 22 21 20

128 64 32 16 8 4 2 1

0 0 1 0 0 1 0 0

32 + 4 = 36

12


Figure 2-1 Base-10 positional notation of 161

7 6 5 4 3 2 1 0

27 26 25 24 23 22 21 20

128 64 32 16 8 4 2 1

1 0 0 1 0 1 1 1

13


'€' '\u20AC'


ASCII Table



Console.WriteLine('\u00D1');

17


18

Memory Locations for Data

customerName, productCode, addressLine1, savingAccountBalance

19

Reserved Words in C#

Contextual Keywords

20

Table 2-4 C# contextual keywords

Never use these words as variable names – It is a very bad idea!!!

21

Naming Conventions

– Eg: FirstName, LastName

– Eg: firstName, lastName, savingAccountBalance

22

Examples of Valid Names (Identifiers)

Table 2-5 Valid identifiers

23

Examples of Invalid Names (Identifiers)

Table 2-6 Invalid identifier

type identifier = expression;

24

Variables


25

Types, Classes, and Objects

int, string


26

Type, Class, and Object Examples

Table 2-7 Sample data types

27

Predefined Data Types

• Common Type System (CTS)

• Divided into two major categories

Figure 2-3 .NET common types

28

Value and Reference Types

Figure 2-4 Memory representation for value and reference types

29

Value Types

Figure 2-5 Value type hierarchy

30

Value Types

• 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)

32

Integral Data Types

– byte & sbyte

– char

– int & uint

– long & ulong

– short & ushort

Data Types

33 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

Floating-Point Types

Table 2-10 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

Decimal Types

• Examples

decimal endowmentAmount = 33897698.26M;

decimal deficit;

Table 2-11 Value and size for decimal data type

38

Boolean Variables

→

false

bool undergraduateStudent;

bool moreData = true;

39

Strings

string studentName;

string courseName = "Programming I";

string twoLines = "Line1\nLine2";

40

Making Data Constant

const

const type identifier = expression;

const double TAX_RATE = 0.0675;

const int SPEED = 70;

const char HIGHEST_GRADE = 'A';

41

Assignment Statements

variable = expression;

42

Examples of Assignment

Statements

int numberOfMinutes,

count,

minIntValue;

numberOfMinutes = 45;

count = 0;

minIntValue = -2147483648;

count = count + 1;

numberOfMinutes = 10 + Delay(clerkId);


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 '€'

43

44


Statements (continued)

double accountBalance,

weight;

bool isFinished;

accountBalance = 4783.68;

weight = 1.7E-3; //scientific notation may be used

isFinished = false; //declared previously as a bool

//Notice – no quotes used

45



decimal amountOwed,

deficitValue;

amountOwed = 3000.50m; // m or M must be suffixed to

// decimal data types

deficitValue = -322888672.50M;

46



string aSaying, fileLocation;

aSaying = "First day of the rest of your life!\n";

fileLocation = @ "C:\textFiles\newChapter2";

@

47



Figure 2-7 Impact of assignment statement

48

Arithmetic Operations

resultVariable = operand1 operator operand2;

49

Basic Arithmetic Operations

Figure 2-8 Result of 67 % 3

50


(continued)

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


(continued)

num++; // num = num + 1;

--value1; // value = value – 1;

int num = 100;

Console.WriteLine(num++); // Displays 100

Console.WriteLine(num); // Displays 101

Console.WriteLine(++num); // Displays 102


(continued)

53

Figure 2-10 Declaration of value type variables


(continued)

54 Figure 2-11 Change in memory after count++; statement executed


55


(continued) int num = 100;

Console.WriteLine(num++); //prints 100

Console.WriteLine(num); //prints 101

Console.WriteLine(++num); //prints 102

56


(continued)

Figure 2-12 Results after statement is executed

57

Compound Operations

58


(continued)

answer = 100;

answer += 50 * 3 / 25 – 4;

50 * 3 = 150

150 / 25 = 6

6 – 4 = 2

100 + 2 = 102

59

Order of Operations

Table 2-14 Operator precedence

60

Order of Operations (continued)

Figure 2-13 Order of execution of the operators

61

Mixed Expressions

double answer; answer = 10 / 3; // Does not produce 3.3333333 double answer2; answer2 = 10.0 / 3; // produces 3.3333333 int value1 = 440, anotherNumber = 70; double value2 = 100.60; value2 = value1; // ok, 440.0 stored in value2

62

Mixed Expressions int value1 = 440; double value2 = 100.60;

value1 = value2; // syntax error as shown in Figure 2-14

double int

63

Mixed Expressions (continued)

(type) expression examAverage = (exam1 + exam2 + exam3) / (double) count;

int value1 = 0,

anotherNumber = 75;

double value2 = 100.99,

anotherDouble = 100;

value1 = (int) value2; // value1 = 100

value2 = (double) anotherNumber; // value2 = 75.0

64

Mixed Expressions (continued)

Convert

int v1 = Convert.ToInt32(1.999); // v1 is 1

long v2 = Convert.ToInt64("5.7777"); // v2 is 5.7777

string v3 = Convert.ToString(1.999); // v3 is "1.999"

char v4 = Convert.ToChar(65); // v4 is 'A'

65

Formatting Output

66

Formatting Output (continued)

Table 2-15 Examples using format specifiers

67

Numeric Format Specifiers

68

Numeric Format Specifiers

(continued)

69

Custom Numeric Format Specifiers

Table 2-17 Custom numeric format specifiers

Custom Numeric Format

Specifiers (continued)

70

Width Specifier

Console.WriteLine("{0,10:F0}{1,8:C}", 9, 14);

9 $14.00 //Right justified values

------------------

123456789012345678

71

Interpolated Strings (New in C# 6)

72

• $•

•

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

74

Data Needs for the

CarpetCalculator

Table 2-18 Variables

75

Nonchanging Definitions for the

CarpetCalculator

Table 2-19 Constants

Side Note: 1 yard = 3 feet

1 sqy = 9 sqf

76

CarpetCalculator Example

77

Algorithm for

CarpetCalculator

Example

Figure 2-17 CarpetCalculator flowchart

78

Algorithm for the


(continued)

Figure 2-18 Structured English for the CarpetCalculator example

79


(continued)

Figure 2-19 Class diagram for the CarpetCalculator example


(continued)

80 Figure 2-20 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

totalCost = numOfSquareYards * carpetPrice;

Console.WriteLine("The cost of " + ECONOMY_CARPET

+ " is " + "{0:C}", totalCost);

Console.Read();

}

}

}

Coding Standards


83

Resources

Naming Guidelines for .NET – http://msdn.microsoft.com/en-us/library/xzf533w0(VS.71).aspx

Writing Readable Code – http://software.ac.uk/resources/guides/writing-readable-source-code#node-131

C# Video tutorials – http://www.programmingvideotutorials.com/csharp/csharp-introduction

Visual Studio 2012 – C# – http://msdn.microsoft.com/en-us/library/kx37x36(V=VS.110).aspx

84

Chapter Summary


85


86

Chapter Summary (continued)


87

Chapter Summary (continued)

• Constants

• Assignment statements

– Order of operations

• Formatting output

88

using System; using System.Globalization; using System.Resources; using System.Threading; class Sample { public static void Main() { Console.WriteLine(String.Format("{0:0.00}", 123.4567)); // 123.46 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)); // 123.00 Console.WriteLine(String.Format("{0:0.00}", 123)); // 123.00 Console.WriteLine(String.Format("{0:00.0}", 123.4567) ); // 123.5 Console.WriteLine(String.Format("{0:00.0}", 1.99) ); // 02.0 Console.WriteLine(String.Format("{0:0,0.0}", 12345.67)); // 12,345.7 Console.WriteLine(String.Format("{0:#.00}", 0.1) ); // .10 Console.WriteLine(String.Format("{0,10:0.0}", 123.4567)); // _____123.5 Console.WriteLine(String.Format("{0,-10:0.0}", 123.4567)); // 123.5____ Console.WriteLine(String.Format("Balance is ${0,-10:0.0}USD", 123.4567)); // Balance is $123.5____USD Console.WriteLine(String.Format("{0:Balance is $0.0 USD}", 123.4567)); // 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:(###) ###-####}", 2165551234)); // (216) 555-1234 Console.WriteLine(String.Format("{0:(000) 000-0000}", 2165551234)); // (216) 555-1234 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(); } }

Appendix 1 Formatting Numbers


89

using System; using System.Globalization; using System.Resources; using System.Threading; class DemoFormatDates { public static void Main() { //using other Culture values. See Link: // https://msdn.microsoft.com/en-US/library/Ee825488(v=CS.20).aspx //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 / 2015 4:39:58 PM Console.WriteLine(String.Format("{0:y yy yyy yyyy}", dt)); // 15 15 2015 2015 Console.WriteLine(String.Format("{0:M MM MMM MMMM}", dt)); // 8 08 Aug August Console.WriteLine(String.Format("{0:d dd ddd dddd}", dt)); // 8 08 Sat Saturday Console.WriteLine(String.Format("{0:h hh H HH}", dt)); // 4 04 16 16 hour 12/24 Console.WriteLine(String.Format("{0:m mm}", dt)); // 39 39 minutes Console.WriteLine(String.Format("{0:s ss}", dt)); // 58 58 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)); // -4 -04 -04:00 time zone Console.ReadKey(); } }

Appendix 2 Formatting Dates


90

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 / 2015 10:22:15 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 / 2015 ShortDate Console.WriteLine(String.Format("{0:D}", dt)); // Saturday, August 08, 2015 LongDate Console.WriteLine(String.Format("{0:F}", dt)); // Saturday, August 08, 2015 10:22:15 PM FullDateTime Console.WriteLine(String.Format("{0:r}", dt)); // Sat, 08 Aug 2015 22:22:15 GMT RFC1123 Console.WriteLine(String.Format("{0:u}", dt)); // 2015 - 08 - 08 22:22:15Z UniversalSortableDate Console.ReadKey(); } }

Appendix 3 Formatting Dates

91

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.WriteLine("----------+===============+-----"); Console.ReadKey(); } }

Appendix 4 Formatting Tables

Documents

Data Types and Expressions - csuohio.edugrail.cba.csuohio.edu/~matos/notes/ist-211/csNotes/9781285096261... · C# Programming: From Problem Analysis to Program Design 1 Data Types