Deitel_Chapter_06_Exercise_13

exercise_06-13.cpp

/*6.13 (Rounding Numbers) An application of function floor is to round a value to it's nearest
integer. The statement

y = floor(x + .5);

rounds the number x to the nearest integrand and assigns the result to y. Write a program that reads
several numbers and uses the preceding statement to round each of these numbers to the nearest
integer. For each number processed, print both the original number and the rounded number.*/

// =============================================== 06-13 =============================================== //

#include <iostream>
#include <iomanip>

// function definitions
void displayPrompts(int& totalEntriesRef)
{
	std::cout << "Enter the total number of entries then press Enter: "; // 1st prompt
	std::cin >> totalEntriesRef; // stream input into totalEntries
	std::cout << "Enter " << totalEntriesRef << " doubles separated by spaces : ";
}

double nearest(double doubleNumber)
{
	return floor(doubleNumber + 0.5);
}

void displayTableHeader()
{
	std::cout << "\n"
		<< std::left << std::setw(5) << "Entry"
		<< std::right << std::setw(10) << "Number"
		<< std::right << std::setw(20) << "Nearest Integer"
		<< std::endl;
}

void displayResults(int  myCount, double  myNumber, double  myNearestInteger)
{
	// display entry count in table
	std::cout << std::left << std::setw(5) << myCount;

	// display number entered by user without trailing zeros or unnecessary decimal point (see link below)
	std::cout << std::right << std::setw(10) << std::noshowpoint << myNumber;

	// display rounded double to nearest integer
	std::cout << std::setw(20) << myNearestInteger << std::endl;	
}

// main
int main()
{
	double number;
	double nearestInteger;
	int totalEntries;
	int count{ 1 }; // iterator used in while loop

	displayPrompts(totalEntries); // note that totalEntries is passed by reference and will be defined in this function

	while (true) // loop to display table with all entries
	{
		std::cin >> number; // (a double) entered by user in function displayPrompts

		// count increments	after each cin stream read from buffer. 
		if (count == 1) // print table header on first pass
			displayTableHeader();

		if (count >= 1) // round to nearest integer, output into a table and increment count
		{
			nearestInteger = nearest(number); // call function nearest to return the nearest integer; assign to nearestInteger
			displayResults(count, number, nearestInteger); // pass by value count, number and nearestInteger
			++count; // increment count after each cin stream pass; 	
		}

		// end when done
		if (count > totalEntries)
		{
			std::cout << std::endl;
			break; // exit loop and end program
		}
	}
} // end of Rounding Numbers exercise

// see: https://www.tutorialspoint.com/cpp_standard_library/cpp_noshowpoint.htm