Chapter 7.4 Multidimensional Arrays

# Chapter 7.4 Multidimensional Arrays

## Chapter 7.4 Multidimensional Arrays

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1. Chapter 7.4Multidimensional Arrays Goals: • To examine the basics of multidimensional arrays in C++

2. Multidimensional Arrays It is possible to declare arrays of more than one dimension in C++. These arrays are essentially arrays of arrays... 52 rows & 7 columns, for a total of 364 double values! double hrsWorked[52][7]; 24 rows, 60 columns, & 60 layers for a total of 79200 integer values! int second[24][60][60]; CS 140

3. A Simple Example The initialization of the two-dimensional array loads the array one row at a time. #include <iostream> using namespace std; void main() { int dozen[3][4] = {11,12,13,14,35,36,37,38,60,70,80,90}; int row; int col; for (row = 0; row < 3; row++) for (col = 0; col < 4; col++) { cout << dozen[row][col]; if (col != 3) cout << " | "; else if (row != 2) cout << endl << " | | | " << endl << "---+----+----+---" << endl << " | | | " << endl; } cout << endl << endl; return; } CS 140

4. A Large Example: Flight Schedules The prototypes may neglect to specify at most one of the dimensions of a multidimensional array parameter. Otherwise, the compiler will be unable to distinguish the dimensions. //////////////////////////////////////////////////////////// // This program reads data from an input file regarding a // // list of scheduled flights, and then outputs this data // // in a readable format to the monitor. // //////////////////////////////////////////////////////////// #include <iostream> #include <iomanip> #include <fstream> #include <string> using namespace std; const int MAX_NBR_FLIGHTS = 10; enum CityCode { Atlanta = 1, Chicago, Dallas, Denver, LosAngeles, NewYork, Seattle }; void loadData(int flightData[][6], int &nbrOfRows); void computeTimes(const int data[][6], int time[], int nbrFlights); int timeChange(CityCode departCity, CityCode arriveCity); void outputChart(const int flyTable[][6], const int minutes[], int nbrRows); void outputFlightInfo(const int flightInfo[], const int minutes); void convertCodeToCity(CityCode city, string cityString); void computeTime(int time, int &hour, int &min, string AMorPM); double computePrice(int nbrMinutes, int nbrMiles); CS 140

5. // The main function coordinates the retrieval of the flight // // data, the calculation of each flight's time in the air, // // and the output of the flight info in a readable format. // void main() { int numberOfFlights; int flightData[MAX_NBR_FLIGHTS][6]; int elapsedTime[MAX_NBR_FLIGHTS]; loadData(flightData, numberOfFlights); computeTimes(flightData, elapsedTime, numberOfFlights); outputChart(flightData, elapsedTime, numberOfFlights); return; } // This function loads a two-dimensional array of integers // // with a prepackaged set of data about various flights. // void loadData(int flightData[][6], int &nbrOfRows) { ifstream flightFile; int flightNbr; nbrOfRows = 0; flightFile.open("flightData.txt"); flightFile >> flightNbr; while (!flightFile.eof()) { flightData[nbrOfRows][0] = flightNbr; // Flight Number flightFile >> flightData[nbrOfRows][1]; // Source City Code flightFile >> flightData[nbrOfRows][2]; // Destination City Code flightFile >> flightData[nbrOfRows][3]; // Departure Time (Military) flightFile >> flightData[nbrOfRows][4]; // Arrival Time (Military) flightFile >> flightData[nbrOfRows][5]; // Distance In Miles nbrOfRows++; flightFile >> flightNbr; } return; } The main function “knows” that the flightData array has 10 rows and 6 columns. The loadData function “knows” that the array has 60 entries and 6 columns, so it “deduces” that there are 10 rows! CS 140

6. // This function calculates the total amount of time, in minutes, // // between each flight's takeoff time and its arrival time. This // // data is stored in the parameterized array named time. // void computeTimes(const int data[][6], int time[], int nbrFlights) { int i, hours, minutes; for (i = 0; i < nbrFlights; i++) { hours = (data[i][4] / 100) - (data[i][3] / 100); if (hours < 0) hours += 24; hours += timeChange(CityCode(data[i][1]), CityCode(data[i][2])); minutes = (data[i][4] % 100) - (data[i][3] % 100); if (minutes < 0) { minutes += 60; hours--; } time[i] = 60 * hours + minutes; } return; } The integer data in columns 1 & 2 of that data array must be typecast to the enumerated CityCode type before being passed to the timeChange function. CS 140

7. // This function uses a seven-city numerical code to determine the // // time difference between two cities, with positive numbers used // // for east-to-west flights, and negative numbers for west-to-east // // flights. Thus, for example, a NY-to-LA flight yields a result // // of 3, while an LA-to-NY flight yields a result of -3. // int timeChange(CityCode departCity, CityCode arriveCity) { int departTimeZone, arriveTimeZone; switch(departCity) { case(Atlanta): case(NewYork): {departTimeZone = 3; break;} case(Chicago): case(Dallas): {departTimeZone = 2; break;} case(Denver): {departTimeZone = 1; break;} case(LosAngeles): case(Seattle): {departTimeZone = 0; break;} } switch(arriveCity) { case(Atlanta): case(NewYork): {arriveTimeZone = 3; break;} case(Chicago): case(Dallas): {arriveTimeZone = 2; break;} case(Denver): {arriveTimeZone = 1; break;} case(LosAngeles): case(Seattle): {arriveTimeZone = 0; break;} } return (departTimeZone - arriveTimeZone); } CS 140

8. // This function outputs the readable table of flight data to the monitor. // void outputChart(const int flyTable[][6], const int minutes[], int nbrRows) { int flight; cout.setf(ios::fixed); cout.setf(ios::showpoint); cout.precision(2); cout << " ICARUS AIRLINES FLIGHT SCHEDULE" << endl << endl << "Flight Departure Departure Arrival Arrival Ticket" << endl << "Number City Time City Time Price" << endl << "------ --------- --------- ------- ------- ------" << endl; for (flight = 0; flight < nbrRows; flight++) outputFlightInfo(flyTable[flight], minutes[flight]); cout << endl << endl; return; } The outputFlightInfo function is being sent a single row of the flyTable 2-D array, as well as a single entry of the minutes 1-D array! CS 140

9. // This function outputs the flight information in the // // parameterized array, using the parameterized integer // // value to assist in computing the ticket price. // void outputFlightInfo(const int flightInfo[], const int minutes) { int hour; int min; string city; string AMorPM[3]; double ticketPrice; cout << ' ' << flightInfo[0] << " "; convertCodeToCity(CityCode(flightInfo[1]), city); cout << city << setw(14-strlen(city)) << ' '; computeTime(flightInfo[3], hour, min, AMorPM); cout << setw(2) << hour << ':'; (min < 10) ? (cout << '0' << min) : (cout << min); cout << AMorPM; convertCodeToCity(CityCode(flightInfo[2]), city); cout << " " << city << setw(15-strlen(city)) << ' '; computeTime(flightInfo[4], hour, min, AMorPM); cout << setw(2) << hour << ':'; (min < 10) ? (cout << '0' << min) : (cout << min); cout << AMorPM; ticketPrice = computePrice(minutes, flightInfo[5]); cout << " \$" << ticketPrice << endl; return; } This function is unaware of the fact that its first parameter is actually a row of a 2-D array, and that its second parameter is actually an entry in a 1-D array! CS 140

10. // This function uses the numerical code associated with a particular // // city to yield the character string representing that city's name. // void convertCodeToCity(CityCode city, string cityString) { switch(city) { case(Atlanta) : {cityString = "Atlanta"; break;} case(Chicago) : {cityString = "Chicago"; break;} case(Dallas) : {cityString = "Dallas"; break;} case(Denver) : {cityString = "Denver”; break;} case(LosAngeles): {cityString = "Los Angeles"; break;} case(NewYork) : {cityString = "New York"; break;} case(Seattle) : {cityString = "Seattle”; break;} } return; } // This function uses the military time represented in the parameter time // // to compute the civilian time in hours and minutes, as well as a string // // indicating whether that time is AM or PM. // void computeTime(int time, int &hour, int &min, string AMorPM) { (time < 1200) ? (AMorPM = "AM”) : (AMorPM = "PM”); hour = ((time/100 - 1) % 12 + 1); min = time % 100; return; } CS 140

11. // This function computes the price of a flight, using \$2.50 // // per minute or \$0.25 per mile, whichever is more expensive. // double computePrice(int nbrMinutes, int nbrMiles) { double timePrice, distancePrice, price; timePrice = 2.50 * nbrMinutes; distancePrice = 0.25 * nbrMiles; price = (timePrice > distancePrice) ? (timePrice) : (distancePrice); return price; } 1182 7 5 510 721 1134 7498 5 3 807 1215 1399 9256 3 1 1250 1529 822 3037 1 6 1620 1755 854 6045 6 2 1854 2000 809 3572 2 4 2101 2212 1021 4168 4 7 2319 103 1341 Input file flightData.txt Resulting output CS 140