CSCI 152 Simple Structures

// GLOBAL TYPE DECLARATIONS

1 struct Date

2 {

3 int month;

4 int day;

5 int year;

6 };

7 struct Machine

8 {

9 int id;

10 bool serviceContract;

11 float failRate;

12 int downDays;

13 float cost,

14 deprValue;

15 };

// LOCAL VARIABLE DECLARATIONS

16 Date yesterday;

17 Date today = { 3, 2, 2004 }; // compile-time initialization

18 Machine press;

19 Machine station [100];

The following statements demonstrate references to fields (fully qualified names must be used for all field identifiers). You can do anything with a field that you can do with a single variable of the same type.

20 cout << "Date: " << today.month << "/"

<< today.day << "/"

<< today.year << endl;

21 cout << "Machine # " << press.id << endl;

22 cout << "Original cost = $" << setiosflags(ios::showpoint)

<< setprecision(2) << press.cost << endl;

23 cout << "Depreciation value = $" << press.deprValue << endl;

24 cout << "# down days since purchase = " << press.downDays << endl;

25 if (press.failRate > MAX_FAIL_RATE)

26 cout << "Excessive downtime\n";

27 if (press.serviceContract == false) // or if(!press.serviceContract)

28 cout << "Service contract has expired\n";

The only defined operations for structure variables (the entire structure) of the same type are:

• assignment
• pass as a parameter to a function (either by value or by reference)
• return by a function

29 yesterday = today;

is equivalent to these three statements:

30 // yesterday.month = today.month;

31 // yesterday.day = today.day;

32 // yesterday.year = today.year;

Another example of structure assignments:

1 station[5] = press;

is equivalent to:

2 station[5].id = press.id;

3 station[5].serviceContract = press.serviceContract;

4 station[5].failRate = press.failRate;

5 station[5].downDays = press.downDays;

6 station[5].cost = press.cost;

7 station[5].deprValue = press.deprValue;

The following statements demonstrate references to elements of an array of structures. Values are input from a text file to be assigned to successive elements of the station array.

char contractCode;

int stationNbr, n;

bool found;

1 stationNbr = 0; // number of elements currently assigned in array

// and subscript of next available array element

2 while (inFile >> station[stationNbr].id >> contractCode))

{

3 if (contractCode == 'Y')

4 station[stationNbr].serviceContract = true;

5 else station[stationNbr].serviceContract = false;

6 inFile >> station[stationNbr].failRate;

7 inFile >> station[stationNbr].downDays;

8 inFile >> station[stationNbr].cost

>> station[stationNbr].deprValue;

9 stationNbr ++ ;

}

// After the station array has been loaded, it can be searched to see if

// a particular machine is represented in the array. For example, the

// following code will search the array to see if there is a match on

// press (assume the press structure variable has been assigned values).

10 n = 0;

11 found = false;

12 while (n < stationNbr && ! found)

13 if (station[n].id == press.id)

14 found = true;

15 else n++;

// If press is not in the array, insert it into the array in the next

// available position, assuming there is space in the array.

16 if (! found)

{

17 station[stationNbr] = press; // structure-to-structure assignment

18 stationNbr++;

}