Deitel_Chapter_06_Exercise_14

exercise_06-14.cpp

/*6.14 (Rounding Numbers) Function floor can be used to round a number to a specific decimal
place.The statement

y = floor(x * 10 + 0.5) / 10;

rounds x to the tenths position(the first position to the right of the decimal point).The statement

y = floor(x * 100 + 0.5) / 100;

rounds x to the hundredths position(the second position to the right of the decimal point).Write
a program that defines four functions to round a number x in various ways:

a) roundToInteger(number)
b) roundToTenths(number)
c) roundToHundredths(number)
d) roundToThousandths(number)

For each value read, your program should print the original value, the number rounded to the
nearest integer, the number rounded to the nearest tenth, the number rounded to the nearest hundredth
and the number rounded to the nearest thousandth.*/

// =============================================== 06-14 =============================================== //

#include <iostream>
#include <iomanip>
#include <cmath>

// function definitions
void displayPrompt(int& totalEntriesRef )
{
	std::cout << "Enter the number entries: ";	// 1st prompt
	std::cin >> totalEntriesRef;				// set variable limit
	std::cout << "Enter " << totalEntriesRef << " numbers separated by spaces: ";
}

void displayTableHeader()
{
	std::cout << std::endl;
	std::cout << std::right << std::setw(60) << "Rounded to the nearest";
	std::cout << std::endl;
	std::cout << std::setfill(' ') << std::setw(22) << " "; 
	std::cout << std::setfill('=') << std::setw(50) << " "; 
	std::cout << std::setfill(' '); // unstick setfill('=') above
	std::cout << "\n"
		<< std::left << std::setw(5) << "Count"
		<< std::right << std::setw(10) << "Number"
		<< std::right << std::setw(14) << "Integer"
		<< std::right << std::setw(14) << "Tenths"
		<< std::right << std::setw(14) << "Hundreths"
		<< std::right << std::setw(14) << "Thousandths"
		<< std::endl;
}

// the function below replaces the four functions suggested in the problem statement
double roundingFunction(double n, int power)
{
	return floor(n * pow(10, power) + 0.5) / pow(10, power);
}

void dispalyResults(int myCount, double myNumber)
{
	std::cout << std::noshowpoint;
	std::cout << std::left << std::setw(5) << myCount;
	std::cout << std::right << std::setw(10) << myNumber;

	for (int i = 0; i <= 3; i++) // iterates powers of ten for roundingFunction	
		std::cout << std::setw(14) << roundingFunction(myNumber, i);	
	
	std::cout << std::endl;
}

// main
int main ()
{
	int totalEntries; // number of inputs made by user
	int count{ 1 }; // an iterator
	double number; // number entered by user

	displayPrompt(totalEntries);		

	while (true)
	{
		std::cin >> number; // stream input by user into variable number
		
		if (count == 1) // print table header		
			displayTableHeader();

		if (count >= 1) // calculate rounding
		{
			dispalyResults(count, number);
			++count; // increments count after each cin stream from buffer; 	
		}

		if (count > totalEntries)
		{
			std::cout << std::endl;
			break; // break out of loop and end program
		}
	}
} // end of exercise_06-14