TWiki> KenyonCpp Web>CodeArray2 (2015-10-05, JimSkon)

### Functions Sample code 2

```//DISPLAY 7.13 Two-Dimensional Array
//Reads quiz scores for each student into the two-dimensional array grade (but
//the input code is not shown in this display). Computes the average score
//for each student and the average score for each quiz. Displays the quiz scores
//and the averages.
#include <iostream>
#include <iomanip>
const int NUMBER_STUDENTS = 4, NUMBER_QUIZZES = 3;

void compute_st_ave(const int grade[][NUMBER_QUIZZES], double st_ave[]);
//Precondition: Global constants NUMBER_STUDENTS and NUMBER_QUIZZES
//are the dimensions of the array grade. Each of the indexed variables
//grade[st_num-1, quiz_num-1] contains the score for student st_num on quiz
//quiz_num.
//Postcondition: Each st_ave[st_num-1] contains the average for student
//number stu_num.

void compute_quiz_ave(const int grade[][NUMBER_QUIZZES], double quiz_ave[]);
//Precondition: Global constants NUMBER_STUDENTS and NUMBER_QUIZZES
//are the dimensions of the array grade. Each of the indexed variables
//grade[st_num-1, quiz_num-1] contains the score for student st_num on quiz
//quiz_num.
//Postcondition: Each quiz_ave[quiz_num-1] contains the average for quiz number
//quiz_num.

void display(const int grade[][NUMBER_QUIZZES],
const double st_ave[], const double quiz_ave[]);
//Precondition: Global constants NUMBER_STUDENTS and NUMBER_QUIZZES are the
//dimensions of the array grade. Each of the indexed variables grade[st_num-1,
//quiz_num-1] contains the score for student st_num on quiz quiz_num. Each
//st_ave[st_num-1] contains the average for student stu_num. Each
//quiz_ave[quiz_num -1] contains the average for quiz number quiz_num.
//Postcondition: All the data in grade, st_ave, and quiz_ave has been output.

int main( )
{
using namespace std;
int grade[NUMBER_STUDENTS][NUMBER_QUIZZES]={20,16,17,19,13,14,19,19,20,17,17,15};//This works too
double st_ave[NUMBER_STUDENTS];
double quiz_ave[NUMBER_QUIZZES];

//The code for filling the array grade goes here, but is not shown.
return 0;
}

void compute_st_ave(const int grade[][NUMBER_QUIZZES], double st_ave[])
{
for (int st_num = 1; st_num <= NUMBER_STUDENTS; st_num++)
{//Process one st_num:
double sum = 0;
for (int quiz_num = 1; quiz_num <= NUMBER_QUIZZES; quiz_num++)
sum = sum + grade[st_num -1][quiz_num -1];
//sum contains the sum of the quiz scores for student number st_num.
st_ave[st_num -1] = sum/NUMBER_QUIZZES;
//Average for student st_num is the value of st_ave[st_num-1]
}
}

void compute_quiz_ave(const int grade[][NUMBER_QUIZZES], double quiz_ave[])
{
for (int quiz_num = 1; quiz_num <= NUMBER_QUIZZES; quiz_num++)
{//Process one quiz (for all students):
double sum = 0;
for (int st_num = 1; st_num <= NUMBER_STUDENTS; st_num++)
sum = sum + grade[st_num -1][quiz_num -1];
//sum contains the sum of all student scores on quiz number quiz_num.
quiz_ave[quiz_num -1] = sum/NUMBER_STUDENTS;
//Average for quiz quiz_num is the value of quiz_ave[quiz_num-1]
}
}

//Uses iostream and iomanip:
void display(const int grade[][NUMBER_QUIZZES],
const double st_ave[], const double quiz_ave[])
{
using namespace std;
cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(1);
cout << setw(10) << "Student"
<< setw(5) << "Ave"
<< setw(15) << "Quizzes\n";
for (int st_num = 1; st_num <= NUMBER_STUDENTS; st_num++)
{//Display for one st_num:
cout << setw(10) << st_num
<< setw(5) << st_ave[st_num-1] << " ";
for (int quiz_num = 1; quiz_num <= NUMBER_QUIZZES; quiz_num++)
cout << setw(5) << grade[st_num -1][quiz_num -1];
cout << endl;
}

cout << "Quiz averages = ";
for (int quiz_num = 1; quiz_num <= NUMBER_QUIZZES; quiz_num++)
cout << setw(5) << quiz_ave[quiz_num -1];
cout << endl;
}

```

Topic revision: r1 - 2015-10-05 - JimSkon

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