#include <iostream>
#include <cstdlib>
#include <fstream>
using namespace std;

const unsigned short MAX_SCORES = 100;

float average( float [], unsigned short );

int main()
{
    char choice, filename[81];
    float scores[MAX_SCORES];
    unsigned short n = 0;
    ifstream infile;
    
    cout << "Are scores to be entered from the keyboard (k) "
         << "or read from a file (f)?\nEnter your choice. ";
    cin.get( choice );
    cout << endl;
    
    switch ( choice ) {
        case 'k':
        case 'K':
            cout << "Enter the scores.  "
                 << "Enter Crtl+Z on a line by itself when finshed.\n";
            cin >> scores[n];
            while ( !cin.eof() ) {
                n++;
                cin >> scores[n];
            }
            break;
        case 'f':
        case 'F':
            cout << "Enter the filename.\n";
            cin >> filename;
            cout << endl;
            
            infile.open( filename );
            if ( infile.fail() ) {
                cout << "\n** File cannot be opened **\n";
                system( "PAUSE" );
                exit( EXIT_FAILURE );
            }
            
            infile >> scores[n];
            while ( !infile.eof() ) {
                n++;
                infile >> scores[n];
            }
            break;
            
            infile.close();
        default:
            cout << "You've entered an invalid choice.  Goodbye.\n";
            system( "PAUSE" );
            exit( EXIT_FAILURE );
    }
    
    cout << "Number of scores: " << n << "\n";
    cout << "Average score: " << average( scores, n );
    
    cout << "\n\n"; system( "PAUSE" );
    return( EXIT_SUCCESS );
}

float average( float scores[], unsigned short num_scores )
{
    float sum = 0.0F;
    
    for ( unsigned short i = 0; i < num_scores; i++ ) {
        sum += scores[i];
    }
    return( sum / float( num_scores ) );
}