CHAPTER 12 RECORDS (Structs)

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CHAPTER 12RECORDS (Structs)
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• In this chapter, you will
• Learn about records (structs)
• Examine various operations on a struct
• Explore ways to manipulate data using a struct
• Learn about the relationship between a struct and
  functions
• Discover how arrays are used in a struct
• Learn how to create an array of struct items

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• Records (Struct)
• struct A collection of fixed number of
  components in which components are accessed by
  name is called a struct. The components may be of
  different types.
• The components of a struct are called the members
  of the struct.
• The general form (syntax) of a struct in C is
• struct typeName
• dataType1 identifier1
• dataType2 identifier2
• .
• .
• .
• dataTypen identifiern

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• In C, struct is a reserved word.
• A semicolon at the end of a struct definition is
  a part of the syntax.

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• struct employeeType
• string firstName
• string lastName
• string address1
• string address2
• double salary
• string deptID
• struct is a definition not a declaration. No
  memory is allocated.
• Memory is allocated when we declare variables.

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• struct studentType
• string firstName
• string lastName
• char courseGrade
• int testScore
• int programmingScore
• double GPA
• //variable declaration
• studentType newStudent
• studentType student

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• Accessing struct Members
• The syntax for accessing a struct member is
• structVariableName.MemberName
• In C, the . (dot) is an operator, called the
  member access operator.

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• newstudent.gpa 0.0
• newStudent.firstName "John"
• newStudent.lastName "Brown"

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• The statement
• cingtgtnewstudent.firstName
• reads the next string from the standard input
  device and stores it in newstudent.firstName.
• The statement
• cingtgtnewstudent.testScoregtgtnewstudent.programmingS
  core
• reads two integer values from the keyboard and
  stores them in newStudent.testScore and
  newStudent.programmingScore, respectively.
• score newStudent.testScore
• newStudent.programmingScore

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• if(score gt 90)
• newStudent.courseGrade 'A'
• else if(score gt 80)
• newStudent.courseGrade 'B'
• else if(score gt 70)
• newStudent.courseGrade 'C'
• else if(score gt 60)
• newStudent.courseGrade 'D'
• else
• newStudent.courseGrade 'F'

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• Assignment
• We can assign the value of one struct variable to
  another struct variable of the same type using an
  assignment statement.

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• student newstudent

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• student newstudent
• This statement is equivalent to the following
  statements
• student.firstName newStudent.firstName
• student.lastName newStudent.lastName
• student.courseGrade newStudent.courseGrade
• student.testScore newStudent.testScore
• student.programmingScore newStudent.programmingS
  core
• student.GPA newStudent.GPA

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• Comparison
• struct variables must be compared member-wise.
• To compare the values of student and newStudent,
  you must compare them member-wise, as follows
• if(student.firstName newStudent.firstName
• student.lastName newStudent.lastName)
• .
• .
• .

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• Input/Output
• There are no aggregate input/output operations on
  struct.
• Data in a struct variable must be read one member
  at a time.
• Contents of a struct must be written one member
  at a time.
• The statement
• coutltltnewStudent.firstNameltlt" "
• ltltnewStudent.lastNameltlt" "
• ltltnewStudent.courseGradeltlt" "
• ltltnewStudent.testScoreltlt" "
• ltltnewStudent.programmingScoreltlt" "
• ltltnewStudent.GPAltltendl
• outputs the content of the struct variable
  newstudent.

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• struct Variables and Functions
• A struct variable can be passed as a parameter
  either by value or by reference.
• A function can return a value of the type struct.

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• void readIn(studentType student)
• int score
• cingtgtstudent.firstNamegtgtstudent.lastName
• cingtgtstudent.testScoregtgtstudent.programmingScor
  e
• cingtgtstudent.GPA
• score newStudent.testScore
  newStudent.programmingScore
• if(score gt 90)
• student.courseGrade 'A'
• else if(score gt 80)
• student.courseGrade 'B'
• else if(score gt 70)
• student.courseGrade 'C'
• else if(score gt 60)
• student.courseGrade 'D'
• else

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• The statement
• readIn(newStudent)
• calls the function readIn.
• The function readIn stores the appropriate
  information in the variable newStudent.

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• void printStudent(studentType student)
• coutltltstudent.firstNameltlt" "
• ltltstudent.lastNameltlt" "
• ltltstudent.courseGradeltlt" "
• ltltstudent.testScoreltlt" "
• ltltstudent.programmingScoreltlt" "
• ltltstudent.GPAltltendl

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• Arrays in Structs
• The two things that are associated with a list
  are the values (that is, elements) and the length
  of the list.
• In the searching and sorting functions that we
  discussed, we needed to pass these two things
  separately to the function.
• The values and the length are both related to a
  list we can define a struct containing both the
  items.
• We need to pass only one parameter not two.

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• const arraySize 1000
• struct listType
• int elementsarraySize //array containing
  the list
• int listLength //length of the list

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• int seqSearch(const listType list, int
  searchItem)
• int loc
• bool found false
• for(loc 0 loc lt list.listLength loc)
• if(list.elementsloc searchItem)
• found true
• break
• if(found)
• return loc
• else
• return 1

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• Structs in Arrays
• Suppose there are 50 full time employees in a
  company.
• Print their monthly pay check and also keep track
  of how much money has been paid year to date.
• Define an employees record.
• struct employeeType
• string firstName
• string lastName
• int personID
• string deptID
• double yearlySalary
• double monthlySalary
• double yearToDatePaid
• double monthlyBonus

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• employeeType employees50

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• The following C code loads the data into the
  employees array.
• We assume that initially yearToDatePaid is 0 and
  that the monthly bonus is determined each month
  based on performance.
• ifstream infile //input stream variable assume
• //that employee.dat file has been opened
• for(counter 0 counter lt 50 counter)
• infilegtgtemployeescounter.firstName
• gtgtemployeescounter.lastName
• gtgtemployeescounter.SSN
• gtgtemployeescounter.deptID
• gtgtemployeescounter.yearlySalary
• employeescounter.monthlySalary
• employeescounter.yearlySalary/1
  2
• employeescounter.yearToDatePaid 0.0
• employeescounter.monthlyBonus 0.0

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• double payCheck //variable to calculate the
  paycheck
• for(counter 0 counter lt 50 counter)
• coutltltemployeescounter.firstNameltlt" "
• ltltemployeescounter.lastNameltlt" "
• payCheck employeescounter.monthlySalary
  
• employeescounter.monthlyBonus
• employeescounter.yearToDatePaid
• employeescounter.yearToDatePaid
  
• payCheck
• coutltltsetprecision(2)ltltpayCheckltltendl

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• Structs within a struct
• Let us consider the following record of an
  employee
• struct employeeType
• string firstname
• string middlename
• string lastname
• string emplID
• string address1
• string address2
• string city
• string state
• string zip
• string hiremonth
• string hireday
• string hireyear

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• string quitmonth
• string quitday
• string quityear
• string phone
• string cellphone
• string fax
• string pager
• string email
• string deptID
• double salary

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• struct nameType
• string firstname
• string middlename
• string lastname
• struct addressType
• string address1
• string address2
• string city
• string state
• string zip

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• struct dateType
• string month
• string day
• string year
• struct contactType
• string phone
• string cellphone
• string fax
• string pager
• string email

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• struct employeeType
• nameType name
• string emplID
• addressType address
• dateType hiredate
• dateType quitdate
• contactType contact
• string deptID
• double salary
• // variable declaration
• employeeType newEmployee
• employeeType employees100

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• newEmployee.salary 45678.00
• newEmployee.name.first "Mary"
• newEmployee.name.middle "Beth"
• newEmployee.name.last "Simmons"
• cingtgtnewEmployee.name.first
• newEmployee.salary newEmployee.salary 1.05
• for(j 0 j lt 100 j)
• cingtgtemployeesj.name.first
• gtgtemployeesj.name.middle
• gtgtemployeesj.name.last

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• PROGRAMMING EXAMPLE SALES DATA ANALYSIS
• A company has six salespeople. Every month they
  go on road trips to sell the companys product.
  At the end of each month, the total sales for
  each salesperson, together with that
  salespersons ID and the month, is recorded in a
  file. At the end of each year, the manager of the
  company wants to see the report in the following
  tabular format

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• ----------- Annual Sales Report -------------
• ID QT1 QT2 QT3 QT4
  Total
• __________________________________________________
  _____________
• 12345 1892.00 0.00 494.00 322.00
  2708.00
• 32214 343.00 892.00 9023.00 0.00
  10258.00
• 23422 1395.00 1901.00 0.00 0.00
  3296.00
• 57373 893.00 892.00 8834.00 0.00
  10619.00
• 35864 2882.00 1221.00 0.00 1223.00
  5326.00
• 54654 893.00 0.00 392.00 3420.00
  4705.00
• Total 8298.00 4906.00 18743.00 4965.00
• Max Sale by SalesPerson ID 57373, Amount
  10619.00
• Max Sale by Quarter Quarter 3, Amount
  18743.00
• QT1 stands for quarter 1 (months 1 to 3), QT2 for
  quarter 2 (months 4 to 6), QT3 for quarter 3
  (months 7 to 9) and QT4 for quarter 4 (months 10
  to 12).

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• The salespeoples IDs are stored in one file
  sales data are stored in another file. The sales
  data is in the following form
• salesPersonID month saleAmount
• .
• .
• .
• The sales data is in no particular order it is
  not ordered by ID.
• Input One file containing each salespersons ID,
  and a second file containing the sales data.
• Output A file containing annual sales report in
  the above format.

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• Problem Analysis and Algorithm Design
• struct salesPersonRec
• string ID //salespersons ID
• double saleByQuarter4 //array to store the
  total
• //sales for each quarter
• double totalSale //salespersons yearly
• //sales amount
• salesPersonRec salesPersonListnoOfSalesPersons
• double totalSaleByQuarter4

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• Read the salespeoples IDs into the array
  salesPersonList and initialize the quarterly
  sales and total sales for each salesperson to 0.

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• For each entry in the file containing the sales
  data,
• 1. Read the salespersons ID, month, and sale
  amount for the month.
• 2. Search the array salesPersonList to locate the
  component corresponding to this salesperson.
• 3. Determine the quarter corresponding to the
  month.
• 4. Update the sales for the quarter by adding the
  sale amount for the month.
• Once the sales data file is processed
• a. Calculate the total sale by salesman.
• b. Calculate the total sale by quarter.
• c. Print the report.

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• The above discussion translates into the
  following algorithm.
• 1. Initialize the array sales.
• 2. Process the sales data.
• 3. Calculate the total sale by salesman.
• 4. Calculate the total sale by quarter.
• 5. Print the report.
• 6. Calculate and print the maximum sale by
  salesman.
• 7. Calculate and print the maximum sale by
  quarter.

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• Function initialize
• void initialize(ifstream indata,
• salesPersonRec list, int listSize)
• int count
• quarterType quarter
• for(count 0 count lt listSize count)
• indatagtgtlistcount.ID //get salespersons ID
• for(quarter QT1 quarter lt QT4
• quarter static_castltquarterTypegt(quart
  er 1))
• listcount.saleByQuarterquarter 0.0
• listcount.totalSale 0.0

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• Function getData
• 1. Read the salespersons ID, month, and sales
  amount for the month.
• 2. Search the array salesPersonList to locate the
  component corresponding to the salesperson.
  (Because the salespeoples IDs are not sorted, we
  will use a sequential search to search the
  array.)
• 3. Determine the quarter corresponding to the
  month.
• 4. Update the sales for the quarter by adding the
  sales amount for the month.
• Suppose that the entry read is
• 57373 2 350
• Here the salespersons ID is 57373, the month is
  2, and sale amount is 350.

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• After processing this entry the array
  salesPersonList is

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• void getData(ifstream infile,
• salesPersonRec list, int listSize)
• int count
• quarterType quarter
• string sID
• int month
• double amount
• infilegtgtsID //Step 1
• while(infile)
• infilegtgtmonthgtgtamount //Step 1
• for(count 0 count lt listSize count)
  //Step 2

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• if(sID listcount.ID)
• if(1 lt month month lt 3) //Step 3
• quarter QT1
• else if(4 lt month month lt 6)
• quarter QT2
• else if(7 lt month month lt 9)
• quarter QT3
• else
• quarter QT4
• listcount.saleByQuarterquarter
  amount
• //Step 4
• break //exit for loop
• //end if
• //end for
• infilegtgtsID //Step 1

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• Function saleByQuarter
• void saleByQuarter(salesPersonRec list, int
  listSize,
• double totalByQuarter)
• quarterType quarter
• int count
• for(quarter QT1 quarter lt QT4
• quarter static_castltquarterTypegt(quarter
  1))
• totalByQuarterquarter 0.0
• for(quarter QT1 quarter lt QT4
• quarter static_castltquarterTypegt(quarter
  1))
• for(count 0 count lt listSize count)
• totalByQuarterquarter
  listcount.saleByQuarterquarter

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• Function totalSaleByPerson This function finds
  the yearly sale amount of each salesman sale.
• void totalSaleByPerson(salesPersonRec list,
• int listSize)
• int count
• quarterType quarter
• for(count 0 count lt listSize count)
• //for each salesperson
• for(quarter QT1 quarter lt QT4 //for each
  quarter
• quarter static_castltquarterTypegt(quarter
  1))
• listcount.totalSale
• listcount.saleByQuarterquarte
  r

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• Function printReport
• 1. Print the heading, that is, the first three
  lines of output.
• 2. Print the data for each salesperson.
• 3. Print the last line of the table.

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• void printReport(ofstream outfile,
  salesPersonRec list,
• int listSize, double saleByQuarter)
• int count
• quarterType quarter
• //Step a
• outfileltlt"----------- Annual Sales Report
  -------------"
• ltltendl
• outfileltltendl
• outfileltlt" ID QT1 QT2 QT3
  "
• ltlt"QT4 Total"ltltendl
• outfileltlt"_____________________________________
  ___________"
• ltlt"_______________"ltltendl
• for(count 0 count lt listSize
  count) //Step b
• outfileltltlistcount.IDltlt" "
• for(quarter QT1 quarter lt QT4

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• outfileltlt"Total " //Step c
• for(quarter QT1 quarter lt QT4
• quarter static_castltquarterTypegt(qua
  rter 1))
• outfileltltsetw(10)ltltsaleByQuarterquarter
• outfileltltendlltltendlltltendl

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• Function maxSaleByPerson
• void maxSaleByPerson(ofstream outData,
• salesPersonRec list, int
  listSize)
• int maxIndex 0
• int count
• for(count 1 count lt listSize count)
• if(listmaxIndex.totalSale lt listcount.totalSa
  le)
• maxIndex count
• outDataltlt"Max Sale by SalesPerson ID "
• ltltlistmaxIndex.ID
• ltlt", Amount "
• ltltlistmaxIndex.totalSaleltltendl

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• Function maxSaleByQuarter
• void maxSaleByQuarter(ofstream outData,
• double saleByQuarter)
• quarterType quarter
• quarterType maxIndex QT1
• for(quarter QT1 quarter lt QT4
• quarter static_castltquarterTypegt(quarte
  r1))
• if(saleByQuartermaxIndex lt
  saleByQuarterquarter)
• maxIndex quarter
• outDataltlt"Max Sale by Quarter Quarter "
• ltltgstatic_castltintgt(maxIndex) 1
• ltlt", Amount "ltltsaleByQuartermaxIndexltlten
  dl

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• Main Algorithm
• 1. Declare the variables.
• 2. Prompt the user to enter the name of the file
  containing the salespersons ID data.
• 3. Read the name of the input file.
• 4. Open the input file.
• 5. If the input file does not exist, exit the
  program.
• 6. Initialize the array salesPersonList. Call the
  function initialize.
• 7. Close the input file containing the
  salespersons ID data.
• 8. Prompt the use to enter the name of the file
  containing sales data.
• 9. Read the name of the input file.
• 10. Open the input file.
• 11. If input file does not exist, exit the
  program.
• 12. Prompt the user to enter the name of output
  file.
• 13. Read the name of the output file.

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• 14. Open the output file.
• 15. To output floating-point numbers in a fixed
  decimal format with the decimal point and
  trailing zero, set the manipulators fixed and
  showpoint. Also, to output floating-point numbers
  to two decimal places, set the precision to two
  decimal places.
• 16. Process sales data. Call the function
  getData.
• 17. Calculate the total sale by quarter. Call the
  function saleByQuarter.
• 18. Calculate the total sale by salesman. Call
  the function totalSaleByPerson.
• 19. Print the report in the tabular form. Call
  function the printReport.
• 20. Find and print the salesperson who produces
  the maximum sales for the year. Call the function
  maxSaleByPerson.
• 21. Find and print the quarter producing the
  maximum sale for the year. Call the function
  maxSaleByQuarter.
• 22. Close files.

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• //Program Sales data analysis
• include ltiostreamgt
• include ltfstreamgt
• include ltiomanipgt
• include ltstringgt
• using namespace std
• const int noOfSalesPerson 6
• enum quarterTypeQT1,QT2,QT3,QT4
• struct salesPersonRec
• string ID //salespersons ID
• double saleByQuarter4
• double totalSale

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• void totalSaleByPerson(salesPersonRec list,
• int listSize)
• void maxSaleByPerson(ofstream outData,
• salesPersonRec list, int
  listSize)
• void maxSaleByQuarter(ofstream outData,
• double saleByQuarter)
• void printReport(ofstream outfile,
• salesPersonRec list, int listSize,
• double saleByQuarter)
• int main()
• //Step 1
• ifstream infile //input file stream
  variable
• ofstream outfile //output file stream
  variable
• char inputfile25 //variable to hold the
  input file name
• char outputfile25 //variable to hold the
  output file name
• double totalSaleByQuarter4 //array to hold
  the
• //sales by quarter

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• coutltlt"Enter SalesPerson ID file name "
  //Step 2
• cingtgtinputfile //Step 3
• coutltltendl
• infile.open(inputfile) //Step 4
• if(!infile) //Step 5
• coutltlt"Cannot open input file."ltltendl
• return 1
• initialize(infile, salesPersonList,
  noOfSalesPerson)
• //Step 6
• infile.close() //Step 7
• coutltlt"Enter sales data file name "
  //Step 8
• cingtgtinputfile //Step 9

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• if(!infile) //Step 11
• coutltlt"Cannot open input file."ltltendl
• return 1
• coutltlt"Enter output file name " //Step
  12
• cingtgtoutputfile //Step 13
• coutltltendl
• outfile.open(outputfile) //Step 14
• outfileltltfixedltltshowpointltltsetprecision(2)
  //Step 15
• getData(infile, salesPersonList,
  noOfSalesPerson)
• //Step 16
• saleByQuarter(salesPersonList,
  noOfSalesPerson,
• totalSaleByQuarter) //Step 17

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• maxSaleByPerson(outfile, salesPersonList,
• noOfSalesPerson) //Step 20
• maxSaleByQuarter(outfile, totalSaleByQuarter)
  
• 
  //Step 21
• infile.close() //Step 22
• outfile.close() //Step 22
• return 0

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• //Place the definitions of the other functions
• //here

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• Sample Run
• Input File Salespeoples IDs
• 12345
• 32214
• 23422
• 57373
• 35864
• 54654

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• Input File Salespeoples Data
• 12345 1 893
• 32214 1 343
• 23422 3 903
• 57373 2 893
• 35864 5 329
• 54654 9 392
• 12345 2 999
• 32214 4 892
• 23422 4 895
• 23422 2 492
• 57373 6 892
• 35864 10 1223
• 54654 11 3420
• 12345 12 322
• 35864 5 892
• 54654 3 893
• 12345 8 494
• 32214 8 9023

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• Output File
• ----------- Annual Sales Report -------------
• ID QT1 QT2 QT3 QT4
  Total
• __________________________________________________
  _____________
• 12345 1892.00 0.00 494.00 322.00
  2708.00
• 32214 343.00 892.00 9023.00 0.00
  10258.00
• 23422 1395.00 1901.00 0.00 0.00
  3296.00
• 57373 893.00 892.00 8834.00 0.00
  10619.00
• 35864 2882.00 1221.00 0.00 1223.00
  5326.00
• 54654 893.00 0.00 392.00 3420.00
  4705.00
• Total 8298.00 4906.00 18743.00 4965.00
• Max Sale by SalesMan ID 57373, Amount
  10619.00
• Max Sale by Quarter Quarter 3, Amount
  18743.00