Dynamically allocated array/sorting

[RodRyan93]

I am looking for assistance in finishing a problem where I need to write a program to dynamically allocate an array large enough to hold a user-defined number of test scores. Once all the numbers are entered, I need to average the test scores and sort them in ascending order. I have managed to accomplish the first two but have been trying for two days to figure out how to sort them. I would like help with the code on how to get this array sorted. This is what I have so far...

//This program averages test scores and displays them in ascending order
//The number of test scores is user defined and the program uses a dynamically allocated array


#include <iostream>
#include <iomanip>
using namespace std;

int main ()
{
double *scores, //To dynamically allocate an array
total = 0.0, // Accumulator
average; // To hold average scores
int numScores, //To hold the number of test scores
count; //Counter variable

//Get the number of test scores
cout << "How many test scores would you like to enter? ";
cin >> numScores;

//Dynamically allocate an array large enough to hold that many test scores

scores = new double[numScores];

//Get the test scores
cout << "Enter the test scores below.\n";
for (count = 0; count < numScores; count++)
{
cout << "Test Score " << (count + 1) << ": ";
cin >> scores[count];
}

//Calculate the total of the scores
for (count = 0; count < numScores; count++)
{
total += scores[count];
}

//Calculate the average test score
average = total / numScores;

//Display the results
cout << fixed << showpoint << setprecision(2);
cout << "Average score is: " << average << endl;

//Free dynamically allocated memory
delete [] scores;
scores = 0; //Make scores point to null.

return 0;
}


Thank you for any advice that is offered.

[jupe]

I would say that simple buble sort could help.

function:(which will be some where below main function )

 void bubbleSort(double x[], int n) {
    bool exchanges;
    do {
       exchanges = false;  // assume no exchanges
       for (int i=0; i<n-1; i++) {
          if (x[i] > x[i+1]) {
             double temp = x[i]; x[i] = x[i+1]; x[i+1] = temp;
             exchanges = true;  // after exchange, must look again
          }
       }
    } while (exchanges);
 }

so just before the main you have to put function definition:

void bubbleSort(double x[], int n);

and just before freeing memory put this code:

bubbleSort(scores,numScores);
for (count = 0; count < numScores; count++)
{
   cout<<"score:"<<count<<" "<<scores[count]<<endl;
}

[RodRyan93]

Thank you jupe for your help. I have tried to add the bubble sort as you suggested but wasn't exactly sure where to put the body of the function (from bool through (exchanges)). Here is what I have after trying:

//This program averages test scores and displays them in ascending order
//The number of test scores is user defined and the program uses a dynamically allocated array

#include <iostream>
#include <iomanip>
using namespace std;

void bubbleSort(double scores[], int numScores);

int main ()
{
double *scores, //To dynamically allocate an array
total = 0.0, // Accumulator
average; // To hold average scores
int numScores, //To hold the number of test scores
count; //Counter variable

//Get the number of test scores
cout << "How many test scores would you like to enter? ";
cin >> numScores;

//Dynamically allocate an array large enough to hold that many test scores

scores = new double[numScores];

//Get the test scores
cout << "Enter the test scores below.\n";
for (count = 0; count < numScores; count++)
{
cout << "Test Score " << (count + 1) << ": ";
cin >> scores[count];
}

//Calculate the total of the scores
for (count = 0; count < numScores; count++)
{
total += scores[count];
}

//Calculate the average test score
average = total / numScores;

//Display the results
cout << fixed << showpoint << setprecision(2);
cout << "Average score is: " << average << endl;

{
bool exchanges;
do {
exchanges = false; // assume no exchanges
for (int i=0; i<numScores-1; i++) {
if (scores[i] > scores[i+1]) {
double temp = scores[i]; scores[i] = scores[i+1]; scores[i+1] = temp;
exchanges = true; // after exchange, must look again
}
}
} while (exchanges);
}

bubbleSort(scores,numScores);
for (count = 0; count < numScores; count++)
{
cout<<"score:"<<count<<" "<<scores[count]<<endl;
}


//Free dynamically allocated memory
delete [] scores;
scores = 0; //Make scores point to null.

return 0;
}




When compiling it I get the following 2 errors:

1>lastchance.obj : error LNK2019: unresolved external symbol "void __cdecl bubbleSort(double * const,int)" (?bubbleSort@@YAXQANH@Z) referenced in function _main

1>C:\Documents and Settings\Owner\My Documents\Visual Studio 2008\Projects\lastchance\Debug\lastchance.exe : fatal error LNK1120: 1 unresolved externals

[jmc]

There is a declaration of bubbleSort in your code but the function body can't be found anywhere you've forgotten to insert that code.
You could also use a quick_sort which would be much faster (as the name suggests...) or even a radix_sort, sorting first the precision bits and afterwards the exponent bits. Though it won't really matter for this small number of elements and a bubble_sort sure is the easiest way.

[RodRyan93]

jmc, thank you for your comments.

I have the following code which I thought was the body of the function:

{
bool exchanges;
do {
exchanges = false; // assume no exchanges
for (int i=0; i<numScores-1; i++) {
if (scores[i] > scores[i+1]) {
double temp = scores[i]; scores[i] = scores[i+1]; scores[i+1] = temp;
exchanges = true; // after exchange, must look again
}
}
} while (exchanges);
}

I am brand new at C++. I'm taking an online course and the instructor is not helpful whatsoever. I have tried numerous things, but am really having difficulty with this chapter on pointers.

[jmc]

Yes, it is. But it doesn't occur in the source code which you posted above.

When building your project the declaration void bubbleSort(double scores[], int numScores); can be found but the function with its body doesn't follow.

You have to include the bubbleSort-function, not only the declaration.

[RodRyan93]

It does occur in the source code I posted above just below the section that says //Display the results. Should it be placed somewhere else?

Does it have to be under the call to the function? I think I tried that in the middle of the night last night and it didn't work either.

[jmc]

Here the whole working program again.

#include <iostream>
#include <iomanip>
using namespace std;

void bubbleSort(double scores[], int numScores);

int main (void){
 double *scores, //To dynamically allocate an array
 total = 0.0, // Accumulator
 average; // To hold average scores
 int numScores, //To hold the number of test scores
 count; //Counter variable

 //Get the number of test scores
 cout << "How many test scores would you like to enter? ";
 cin >> numScores;

 //Dynamically allocate an array large enough to hold that many test scores

 scores = new double[numScores];

 //Get the test scores
 cout << "Enter the test scores below.\n";
 for (count = 0; count < numScores; count++){
  cout << "Test Score " << (count + 1) << ": ";
  cin >> scores[count];
 }

 //Calculate the total of the scores
 for (count = 0; count < numScores; count++){
  total += scores[count];
 }

 //Calculate the average test score
 average = total / numScores;

 //Display the results
 cout << fixed << showpoint << setprecision(2);
 cout << "Average score is: " << average << endl;


 bubbleSort(scores,numScores);
 for (count = 0; count < numScores; count++){
  cout<<"score "<<(count+1)<<": "<<scores[count]<<endl;
 }


 //Free dynamically allocated memory
 delete [] scores;
 scores = 0; //Make scores point to null.
 cin.ignore(INT_MAX, '\n');
 cin.ignore(INT_MAX, '\n');

 return 0;
}


void bubbleSort(double scores[], int numScores){
 bool exchanges;
 do{
  exchanges = false; // assume no exchanges
  for(int i = 0; i < numScores - 1; i++){
   if(scores[i] > scores[i + 1]){
    double temp = scores[i];
    scores[i] = scores[i+1];
    scores[i+1] = temp;
    exchanges = true; // after exchange, must look again
   }
  }
 }while(exchanges);
}

[RodRyan93]

Thank you so much. I am not able to run it right now, but will be able to later today. Thanks again!

[RodRyan93]

Thank you again to jupe and jmc. The two of you combined to get me the help I needed. As a 16-year old just starting out with C++ this environment is very intimidating. I appreciate the kindness you showed to me. I was able to finish this problem and go on to do the following problem as well. Ryan

[smilodon]

if you still have time try to use insertion, it hs similar characteristics, but unlike bubble sort, it should be used occasionally.