help in finding average of a class of numbers

This is a discussion on help in finding average of a class of numbers within the C++ Programming forums, part of the General Programming Boards category; well i have this program that i have written error free but my return keeps coming out wrong can anyone ...

  1. #1
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    help in finding average of a class of numbers

    well i have this program that i have written error free but my return keeps coming out wrong can anyone help me resolve this issue. I am including my source code.


    Code:
    #include <iostream>
    #include <fstream> // I/O
    #include <iomanip> // For setw()
    using namespace std;
    
    
    const int MAX_FILE_NAME = 35; // Maximum space allocated for file name
    
    void open_input(ifstream& input, char name[]); // Get file name & Open file
    double find_average(ifstream& input, double& average); // Find avg values
    void output(const char name[], double find_average, ostream& os = cout); // Print 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 average = 0.0;
    double avag = 0;
    // Maximum and minimum numbers from file
    
    cout << "This program can find the average numbers in a file\n"
    << "of doubles.\n" << endl;
    system("pause"); // Hold message on screen until key is pressed
    
    do
    {
    //system("cls"); // Clear screen
    open_input(input_numbers, file_name); // Get file name & open file
    find_average(input_numbers, average); // Find average values in file
    
    input_numbers.close(); // Close file
    output(file_name, avag);
    
    
    
    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;
    
    
    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);// Gets at most MAX_FILE_NAME characters
    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()
    
    double find_average(ifstream& input, double& average) // Find max & min values
    // Parameters: Variables for file reference and max and min values
    // Returns: None
    // Calls: None
    {
    double value;
    
    double sum = 0;
    int count = 0;
    
    while (input >> value) // Continue as long as we can read a number from file.
    {
    average = sum/count;
    sum += value;
    count = count + 1;
    }
    return sum/count;
    } // End of average file
    
    void output(const char name[], double average, ostream& os) // Print results
    // Parameters: File name, max & min values from file, output stream
    // Returns: None
    // Calls: None
    { os << "\n\nInput your File Name Please : " << name << endl;
    os << "Your average : " << setw(8) << average<< endl;
    
    }

  2. #2
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    ican'treadyourcodebecauseyouhaven'tindenteditatall .

  3. #3
    and the Hat of Guessing tabstop's Avatar
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    I now have a headache, but I read enough of your code to discover that you do calculate the average correctly, but don't care about it enough to actually keep it, instead discarding it before your print statement. You have to assign the return value of your function call to avag, if you want avag to actually be the average.

  4. #4
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    Quote Originally Posted by tabstop View Post
    I now have a headache, but I read enough of your code to discover that you do calculate the average correctly, but don't care about it enough to actually keep it, instead discarding it before your print statement. You have to assign the return value of your function call to avag, if you want avag to actually be the average.
    ok so i changed my return function to (return avag) and go a successful build but i still didnt get a correct average in return i am still getting a 0 average and i just need to know where that function call needs to be changed at in order to get the correct average that i am looking for in this program. so here is what i have so far after i change that function call

    Code:
    #include <iostream>
    #include <fstream> // I/O
    #include <iomanip> // For setw()
    using namespace std;
    
    
    const int MAX_FILE_NAME = 35; // Maximum space allocated for file name
    
    void open_input(ifstream& input, char name[]); // Get file name & Open file
    double find_average(ifstream& input, double& average); // Find avg values
    void output(const char name[], double find_average, ostream& os = cout); // Print 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 average = 0.0;
    double avag = 0;
    // Maximum and minimum numbers from file
    
    cout << "This program can find the average numbers in a file\n"
    << "of doubles.\n" << endl;
    system("pause"); // Hold message on screen until key is pressed
    
    do
    {
    //system("cls"); // Clear screen
    open_input(input_numbers, file_name); // Get file name & open file
    find_average(input_numbers, average); // Find average values in file
    
    input_numbers.close(); // Close file
    output(file_name, avag);
    
    
    
    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;
    
    
    return avag;
    } // 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);// Gets at most MAX_FILE_NAME characters
    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()
    
    double find_average(ifstream& input, double& average) // Find max & min values
    // Parameters: Variables for file reference and max and min values
    // Returns: None
    // Calls: None
    {
    double value;
    
    double sum = 0;
    int count = 0;
    
    while (input >> value) // Continue as long as we can read a number from file.
    {
    average = sum/count;
    sum += value;
    count = count + 1;
    }
    return sum/count;
    } // End of average file
    
    void output(const char name[], double average, ostream& os) // Print results
    // Parameters: File name, max & min values from file, output stream
    // Returns: None
    // Calls: None
    { os << "\n\nInput your File Name Please : " << name << endl;
    os << "Your average : " << setw(8) << average<< endl;
    
    }

  5. #5
    Registered User hk_mp5kpdw's Avatar
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    Quote Originally Posted by hastefan2001 View Post
    well i have this program that i have written error free but my return keeps coming out wrong can anyone help me resolve this issue. I am including my source code.
    If it's "coming out wrong" then it isn't error free. It may compile without errors but there are still logic errors causing your symptoms.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  6. #6
    and the Hat of Guessing tabstop's Avatar
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    If you think this line:
    Code:
    find_average(input_numbers, average); // Find average values in file
    does anything at all, you are mistaken.

    Shame-faced edit: Oh hey, there is a & on that function after all. In that case, you should have been setting average instead of returning it. (Note that as it stands, average is set one time too soon in the loop and won't have the last value in it.)
    Last edited by tabstop; 06-29-2009 at 02:22 PM.

  7. #7
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    You are passing average by reference
    For output
    Code:
    output(file_name, avag);
    Where is avag set? Aren't you passing average by reference
    to find_average function?
    Shouldn' that be :
    Code:
    output(file_name, average);

  8. #8
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    thanks

    thanks all for your help in the forum i have been working on that for the past week and i could not quite pinpoint what the problem was right off hand and if i have 'any pther problems i will surly ask i hope that was what my boss was looking for

    thanks
    haste

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