PA 5 - Round Function

// Christian Ballard
// COSC 1336 - 001
// Febuary 4, 2015
// This program should take values from the user and round them using a function.
#include<iostream>
#include<limits>
#include<iomanip>
#include<cctype>
#include<string>
using namespace std;

// Prototypes
double round(double, int);
int readInt(string errorMsg = "", const int = INT_MIN, const int = INT_MAX);
double readDouble(string errorMsg, double min, double max);

int main()
{
    double value;   // Stores the number the user wants to round.
    int decPlaces;  // Stores the number of decimal place the user wants to round to.
    double decPlaces2; // Dublicates the users input to keep from altering it when calling a function.


    cout << "Please enter the number you would like to be rounded. \n You can enter 0 to exit. " << endl;
    value = readDouble("The number", -DBL_MAX, DBL_MAX);


    cout << "What would you like to round to?" << endl;
    decPlaces = readInt("The number", -6, 6);


    decPlaces2 = round(value, decPlaces);


    cout << fixed << setprecision(6);

    cout << "Your rounded number is " << decPlaces2 << endl;



    system("pause");
    return 0;
}
// Takes the users input and rounds it to the decimal place the user inputs.
double round(double userWhole, int userDecimal)
{
    bool negative = false;
    double qwerty;

    if (userWhole < 0) {
        negative = true;
        userWhole = fabs(userWhole);
    }

    qwerty = pow(10.0, userDecimal);
    userWhole *= qwerty;
    userWhole += .5;
    userWhole = floor(userWhole);
    userWhole /= qwerty;

    if (negative == true) {
        userWhole *= -1;
    }

    return userWhole;
}

//*****************************readInt************************************
//Description: Reads and validates an integer in the range between min and max.
//      errorMsg: describes to user the type of data to reenter if error encountered
//      min: the minimum acceptable value
//      max: the maximum acceptable value
//Precondition: user has been prompted for input
//  errorMsg may be assigned a value, default argument is empty string
//  min and max may be assigned values, default arguments are system defaults for int
//  uses header files: iostream, string, limits, cctype
// postcondition: a valid integer in the range min to max is returned
int readInt(string errorMsg, int min, int max)
{
    int someInt;        // Stores each integer entered
    bool valid = false; // Loop control flag indicating validdity of entry
                        // initially assuming not valid.
    do
    {
        // Read an ineger delimited by a whitespace character
        cin >> someInt;

        // Valid if within min to max range.
        valid = someInt >= min && someInt <= max;

        // Detect and remove invalid input
        if (cin.fail() || !valid || !isspace(cin.peek()))
        {
            cout << "\nError! Invalid input.\n" << " must be a whole "
                << "number between " << min << " and " << max << ". \nTry Again: ";

            cin.clear();        // Clears the fail state.

            // Remove up to max number of chars in input stream or up to '\n'.
            cin.ignore(numeric_limits<streamsize>::max(), '\n');

            valid = false;      // No valid entry has been read.
        }

    } while (!valid); // Loop again, prompting user to re-enter a valid integer.

    // When valid input received, remove from input stream up to 100 remaining
    // characters or until reaches the '\n' <ENTER> character.
    cin.ignore(100, '\n');

    return someInt; // Returns a valid integer to calling environment.
}

double readDouble(string errorMsg, const double min, const double max)
{
    double someDouble;      // Stores each double entered.
    bool valid = false;     // Loop control flag indeicating validdity of entry
    // initially assuming not valid.
    do
    {
        // Read an integer delimited by a whitespace character.
        cin >> someDouble;

        // Valid if within min to max range.
        valid = someDouble >= min && someDouble <= max;

        // Detect and remove invalid input.
        if (cin.fail() || !valid || !isspace(cin.peek()))
        {
            cout << "\nError! Invalid input.\n" << errorMsg << " must be a whole "
                << "number between " << min << " and " << max << ". \nTry Again: ";

            cin.clear();        // Clears the fail state.

            // Remove up to max number of chars in input stream or up to '\n'.
            cin.ignore(numeric_limits<streamsize>::max(), '\n');

            valid = false;      // No valid entry has been read.
        }
    } while (!valid); // Loop again, prompting user to re-enter a valid integer.

    // When valid input received, remove from input stream up to 100 remaining
    // characters or until reaches the '\n' <ENTER> character.
    cin.ignore(100, '\n');

    return someDouble; // Returns a valid double to calling environment.
}