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// Purpose: A program that will take input from a file of numbers type double and output the average of the
// numbers to the screen. Using a function that will receive input file stream as a parameter,
// read the file, find and return the average of the numbers.
// Output file name and average
// Allow to process multiple files in one run
//
#include <iostream>
#include <fstream> // I/O
#include <iomanip> // For setw()
using namespace std;
ofstream outputfile("output.txt");
const int MAX_FILE_NAME = 35; // Maximum space allocated for file name
void open_input(ifstream& input, char name[]); // Get file name & Open file
void find_average(ifstream& input, double& sum, double& count, double& solution); // Find average of grades
void output(const char name[], double solution, ostream& os = cout); // Display and file results
int main()
// Parameters: None
// Returns: Zero
// Calls: open_input(), find_max_min(), output()
{ char again; // Does user want to go through loop again?
char file_name[MAX_FILE_NAME + 1]; // Name of file to be processed
ifstream input_numbers; // For working with input file
double sum, count, solution; // Average of grades from file
cout << "This program will average the numbers in a file\n"
<< "of gradess.\n" << endl;
system("pause"); // Hold message on screen until key is pressed
do
{
// Clear screen
open_input(input_numbers, file_name); // Get file name & open file
find_average(input_numbers, sum, count, solution); // Find average of file values
input_numbers.close(); // Close file
output(file_name, solution); // Print results on screen
output(file_name, solution, outputfile); // Print results on outputfile
cout << "\nDo you want to process another file (Y/N)? ";
cin >> again;
cin.ignore(256, '\n'); // Remove Enter key from keyboard buffer
} while ( again == 'y' || again == 'Y');
cout << "\nEnd of Program!" << endl;
outputfile << "\n\nThanks!\n";
outputfile.close();
return 0;
} // End of main()
void open_input(ifstream& input, char name[]) //Open file, exit on error
// Parameters: Variables for input file reference and input file name
// Returns: None
// Calls: None
{ int count = 0; // Count number of tries
do // Continue until we get a valid file name and can open file
{
count++;
if (count != 1) // Issue error message if we are trying again.
{ cout << "\n\aInvalid file name or file does not exist. Please try again."
<< endl;
}
cout << "\nEnter the input file name (maximum of " << MAX_FILE_NAME
<< " characters please)\n:> ";
cin.get(name, MAX_FILE_NAME + 1);//
cin.ignore(256, '\n'); // Remove Enter key from keyboard buffer
input.clear(); // Clear all error flags, if any, from prev try
input.open(name, ios_base::in); // Open only if file exists
} while (input.fail() ); // If can't open file, try again
} // End of open_input()
void find_average(ifstream& input, double& sum, double& count, double& solution) // Find average of data
// Parameters: Variables for file reference and average values
// Returns: None
// Calls: None
{
double num = 0; // Value from file
sum = 0;
count = 0;
solution = 0;
input >> num; // Read first number
while (input >> num) // Continue as long as we can read a number from file.
{
sum=sum+num;
count++;
input >> num;
}
if (count > 0)
{
solution=sum/count;
}
} // End of find_max_min()
void output(const char name[], double solution, ostream& os) // Print results
// Parameters: File name, max & min values from file, output stream
// Returns: None
// Calls: None
{ os << "\n\nInput File Name: " << name << endl;
os << "Grade Average : " << setw(8) << solution << endl;
} // End of output()
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