Test Scores - input validation - c++

Question

so the program needs to dynamically allocate an array large enough to hold a user=defined number of test scores. once all scores are entered, the array should be passed to a function that sorts them in ascending order. another function should be called that calculates the average score. the program should display the sorted list of scores and averages with appropriate headings. use pointer notation rather than array notation whenever possible.
the problem i am having is making it so that the program doesn't accept negative numbers for test scores.
here is the code.
source.cpp
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
void arrSelectSort(float *, int);
void showArrPtr(float *, int);
void showAverage(float, int);
int main()
{
float *scores, //To dynamically allocate an array
total = 0.0, //Accumulator
average; //To hold the averge scores
int numScores; //To hold the number of test scores
//Get the number of test scores.
cout << "How many test scores would you like to process?";
cin >> numScores;
//Dynamically allocate an array large enough to hold that many
//test scores
scores = new float[numScores];
if (scores == NULL)
return 0;
//Get the test score for each test
cout << "Enter the test scores below.\n";
for (int count = 0; count < numScores; count++)
{
cout << "Test score #" << (count + 1) << ": ";
cin >> scores[count];
while (scores <= 0)
{
cout << "Zero or negative numbers not accepted.\n";
cout << "Test Score #" << (count + 1) << ": ";
cin >> scores[count];
}
}
//Calculate the total scores
for (int count = 0; count < numScores; count++)
{
total += scores[count];
}
//sort the elements of the array pointers
arrSelectSort(scores, numScores);
//Will display them in sorted order.
cout << "The test scores in ascending order are: \n";
showArrPtr(scores, numScores);
showAverage(total, numScores);
//Free memory.
delete[] scores;
return 0;
}
void arrSelectSort(float *array, int size)
{
int startScan, minIndex;
float minElem;
for (startScan = 0; startScan < (size - 1); startScan++)
{
minIndex = startScan;
minElem = array[startScan];
for (int index = startScan + 1; index < size; index++)
{
if (array[index] < minElem)
{
minElem = array[index];
minIndex = index;
}
}
array[minIndex] = array[startScan];
array[startScan] = minElem;
}
}
void showArrPtr(float *array, int size)
{
for (int count = 0; count< size; count++)
cout << array[count] << " ";
cout << endl;
}
void showAverage(float total, int numScores)
{
float average;
//Calculate the average
average = total / numScores;
//Display the results.
cout << fixed << showpoint << setprecision(2);
cout << "Average Score: " << average << endl;
system("pause");
}
modified source.cpp to use double instead of float
#include <iostream>
#include <iomanip>
using namespace std;
void arrSelectSort(double *, int);
void showArrPtr(double *, int);
double showAverage(double, int);
int main()
{
double *scores, //To dynamically allocate an array
total = 0.0, //Accumulator
average; //To hold the averge scores
int numScores; //To hold the number of test scores
//Get the number of test scores.
cout << "How many test scores would you like to process?";
cin >> numScores;
//Dynamically allocate an array large enough to hold that many
//test scores
scores = new double[numScores];
if (scores == NULL)
return 0;
//Get the test score for each test
cout << "Enter the test scores below.\n";
for (int count = 0; count < numScores; count++)
{
cout << "Test score #" << (count + 1) << ": ";
cin >> scores[count];
while (scores[count] <= 0)
{
cout << "Zero or negative numbers not accepted.\n";
cout << "Test Score #" << (count + 1) << ": ";
cin >> scores[count];
}
}
//Calculate the total scores
for (int count = 0; count < numScores; count++)
{
total += scores[count];
}
//sort the elements of the array pointers
arrSelectSort(scores, numScores);
cout << "The test scores in ascending order are: \n";
showArrPtr(scores, numScores);
showAverage(total, numScores);
delete[] scores;
return 0;
}
void arrSelectSort(double *array, int size)
{
int startScan, minIndex;
double minElem;
for (startScan = 0; startScan < (size - 1); startScan++)
{
minIndex = startScan;
minElem = array[startScan];
for (int index = startScan + 1; index < size; index++)
{
if (array[index] < minElem)
{
minElem = array[index];
minIndex = index;
}
}
array[minIndex] = array[startScan];
array[startScan] = minElem;
}
}
void showArrPtr(double *array, int size)
{
for (int count = 0; count< size; count++)
cout << array[count] << " ";
cout << endl;
}
double showAverage(double total, int numScores)
{
double average;
//Calculate the average
average = total / numScores;
//Display the results.
cout << fixed << showpoint << setprecision(2);
cout << "Average Score: " << average << endl;
system("pause");
}
errors -
Severity Code Description Project File Line Suppression State
Error C4716 'showAverage': must return a value ConsoleApplication9 c:\users\kenny\desktop\kenny_fepc1.cpp 85
Severity Code Description Project File Line Suppression State
Warning C4101 'average': unreferenced local variable ConsoleApplication9 c:\users\kenny\desktop\kenny_fepc1.cpp 12
please help fix. thank you.

Answer 1

You are not checking for the value that was input:
while (scores <= 0)
should be
while (scores[count] <= 0)
I guess this is homework and you are requested to use c-style arrays. However, please note that using a std::vector would make the task very much simpler as it has a dynamic size (that you dont have to handle "manually") and sorting a vector is trivial.
Btw I would suggest you to change the loop to
for (int count = 0; count < numScores; count++) {
scores[count] = -1;
while (scores[count] <= 0) {
cout << "Test Score #" << (count + 1) << "(has to be >0) : ";
cin >> scores[count];
}
}
Duplicate code is always a pain in the ass when you want to make changes to the code. Try to avoid it whenever possible (even if it is only two small lines).
Your other error appears because your showAverage is declared to return a double but it has no return. Either declare it to return nothing:
void showAverage(double total, int numScores)
or add a return statement at the end of the function:
return average;