Introduction to Algorithms and Data Structures. Structuring Data: Multidimensional Arrays, Arrays of Structures, and Structures Containing Arrays

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1 Introduction to Algorithms and Data Structures Structuring Data: Multidimensional Arrays, Arrays of Structures, and Structures Containing Arrays

2 grades.cpp #include <iostream.h> const int numstudents = 30, numexams = 4; void readgrades(int grades[][numexams]); void findaverages(int averages[], int grades[][numexams]); void writegrades(int grades[][numexams], int averages[]);

3 // CalcAverages() - Calculate the term // averages for a class // The average is based on // four exams int main(void) int grades[numstudents][numexams]; int averages[numstudents]; //Get the grades, find the averages and //print them readgrades(grades); findaverages(averages, grades); writegrades(grades, averages); return(0);

4 // readgrades() - Read the complete set of grades void readgrades(int grades[][numexams]) int i, j; // Get each students grade for (i = 0; i < numstudents; i++) //Get the next grade for this student for (j = 0; j < numexams; j++) cout << "Grade on test #" << j << " for student # " << i << "\t?"; cin >> grades[i][j]; //Skip one line for clarity cout << '\n';

5 // FindAverages() - Find the average for each // student void findaverages(int averages[], int grades[][numexams]) int i, j, sum; for (i = 0; i < numstudents; i++) sum = 0; for (j = 0; j < numexams; j++) sum += grades[i][j]; averages[i] = sum/numexams;

6 // WriteAverage() - Output the grades and // average for each student void writegrades(int grades[][numexams], int averages[]) int i, j; // Print a heading cout << "Student Exam1\tExam2\tExam3\tExam4 << \taverage" << endl;

7 for (i = 0; i < numstudents; i++) // Number each line, then print the grades // and the average for the enxt student cout << i; for (j = 0; j < numexams; j++) cout << '\t'; cout.width(4); cout << grades[i][j]; cout << '\t' << averages[i] << endl;;

8 grades2.cpp #include <iostream.h> #include <iomanip.h> const int maxstudents = 30, numexams = 4; void readgrades(int grades[][numexams], int &numstudents); void findaverages(int averages[], int grades[][numexams], int numstudents); void writegrades(int grades[][numexams], int averages[], int numstudents);

9 // CalcAverages() - Calculate the term // averages for a class // The average is based on // four exams int main(void) int grades[maxstudents][numexams]; int averages[maxstudents]; int numstudents; //Get the grades, find the averages and // print them readgrades(grades, numstudents); findaverages(averages, grades, numstudents); writegrades(grades, averages, numstudents); return(0);

10 // readgrades() - Read the complete set of grades void readgrades(int grades[][numexams], int &numstudents) int j; cout << " Enter a negative grade for exam 1 << to finish" << endl; numstudents = 0; //There are no students yet

11 // Get each students grade do //Get the first exam grades. If it's // non-negative, get the rest. If // it IS negative, there are no more // students. cout << "Grade on test #1" << " for student # " << numstudents+1 << "\t?"; cin >> grades[numstudents][0]; if (grades[numstudents][0] < 0) break;

12 for (j = 1; j < numexams; j++) cout << "Grade on test #" << j+1 << " for student # " << numstudents+1 << "\t?"; cin >> grades[numstudents][j]; //Skip a line for clarity cout << '\n'; numstudents++; while (numstudents < maxstudents); if (numstudents == maxstudents) --numstudents;

13 // FindAverages() - Find the average for each // student void findaverages(int averages[], int grades[][numexams], int numstudents) int i, j, sum; for (i = 0; i < numstudents; i++) sum = 0; for (j = 0; j < numexams; j++) sum += grades[i][j]; averages[i] = sum/numexams;

14 // WriteAverage() - Output the grades and // average for each student void writegrades(int grades[][numexams], int averages[], int numstudents) int i, j; // Print a heading cout << "Student Exam1\tExam2\tExam3\tExam4 << \taverage" << endl;

15 for (i = 0; i < numstudents; i++) // Number each line, then print the grades // and the average for the next student cout << i; for (j = 0; j < numexams; j++) cout << '\t << setw(4) << grades[i][j]; cout << '\t' << averages[i] << endl;;

16 multmat.cpp #include <iostream.h> const int numrows = 4, numcolumns = 4; void readmatrix(int matrix[][numcolumns]); void multmatrix(int c[][numcolumns], int a[][numcolumns], int b[][numcolumns]); void writematrix(int matrix[][numcolumns]);

17 // multmat() Read and multiply two matrices int main(void) int a[numrows][numcolumns], b[numrows][numcolumns], c[numrows][numcolumns]; cout << "Enter matrix a" << endl; readmatrix(a); cout << "Enter matrix b" << endl; readmatrix(b); multmatrix(c, a, b); cout << "The product is:" << endl; writematrix(c); return(0);

18 //readmatrix() - Read in a matrix void readmatrix(int matrix[][numcolumns]) int i, j; for (i = 0; i < numrows; i++) cout << "Enter row #" << i+1 << "\t?"; for (j = 0; j < numcolumns; j++) cin >> matrix[i][j];

19 // multmatrix() Multiply a x b to get c void multmatrix(int c[][numcolumns], int a[][numcolumns], int b[][numcolumns]) int i, j, k; for (i = 0; i < numrows; i++) for (j = 0; j < numcolumns; j++) c[i][j] = 0; for (k = 0; k < numrows; k++) c[i][j] += a[i][k]*b[k][j];

20 // writematrix() Write an i x j matrix void writematrix(int matrix[][numcolumns]) int i, j; for (i = 0; i < numrows; i++) for (j = 0; j < numcolumns; j++) cout << '\t' << matrix[i][j]; cout << '\n'; dl;

21 deanslist.cpp #include #include #include <iostream.h> <string.h> <iomanip.h> // We can have up to 15 student records const int maxstudents = 15; typedef struct char firstname[10]; char lastname[15]; int year; // Year of graduation float gpa; studentrec;

22 // ReadRecords() - reads ALL the student // records void readrecords(studentrec students[], int &numstudents); //WriteRecord() - writes only one record // at a time void writerecord(studentrec students); // DeansList() - Read Student records and print // the Data on studetns on the // Dean's List int main(void) studentrec students[maxstudents]; int i, numstudents;

23 //Input the data readrecords(students, numstudents); //Print the data for students with // gpa's of 3.5 or higher for (i = 0; i < numstudents; i++) if (students[i].gpa >= 3.5) writerecord(students[i]); return(0);

24 //ReadRecords() - Read in the input records void readrecords(studentrec students[], int &numstudents) //Tell the user how to end the input cout << "Enter \"end\" to indicate no more << students" << endl; //Initially, no student records have been // entered numstudents = 0;

25 // For each student, input the first and last // name, year of graduation and grade point // average for (numstudents = 0; numstudents < maxstudents; numstudents++) cout << " First name\t?"; cin >> students[numstudents].firstname; //If they entered "end", there aren't any // more records if (strcmp(students[numstudents].firstname, "end") == 0) break;

26 cout << " Last name\t?"; cin >> students[numstudents].lastname; cout << "Year\t?"; cin >> students[numstudents].year; cout << " Grade point average\t?"; cin >> students[numstudents].gpa;

27 //WriteRecord() - Enter the student record void writerecord(studentrec student) // Make sure that all significant places print cout.setf(ios::showpoint); //Print the record, using four spaces for year and gpa cout << student.firstname << '\t' << student.lastname << '\t' << setw(4) << student.year << '\t' << setw(4) << setprecision(2) << student.gpa << endl;

Introduction to Algorithms and Data Structures

Introduction to Algorithms and Data Structures Lecture 4 Structuring Data: Multidimensional Arrays, Arrays of Objects, and Objects Containing Arrays Grouping Data We don t buy individual eggs; we buy them