/* C++ Programming, Example answer, Exercise 1, Sheet 3  */

/* Author: Rob Miller and William Knottenbelt
   Date last modified: 30th September 2003 */

/* This program prints out a conversion table of temperatures, after
prompting the user for upper and lower bounds of the table in Fahrenheit, 
and the temperature difference between table entries. */ 

#include <iostream>
#include <iomanip>
using namespace std;

double celsius_of(int fahr);
double absolute_value_of(int fahr);

void print_preliminary_message();
void input_table_specifications(int& lowest_entry, int& highest_entry, int& step_size);
void print_message_echoing_input(int lowest_entry, int highest_entry, int step_size); 
void print_table(int lowest_entry, int highest_entry, int step_size); 

/* START OF MAIN PROGRAM */
int main() 
{	
	int lower = 0;  /* for the lowest Fahrenheit entry in the table */
	int upper = 0;  /* for the highest Fahrenheit entry in the table */
	int step = 1;   /* for the difference in Fahrenheit between entries */

	/* set the tabbing functions in iostream.h to left-justify */
	cout << setiosflags (ios::left);

	/* print a message explaining what the program does: */
	print_preliminary_message();

	/* prompt the user for table specifications in Fahrenheit: */
	input_table_specifications(lower, upper, step);
	
	/* print an appropriate message including an echo of the input: */
	print_message_echoing_input(lower, upper, step);
	
	/* Print the table (including the column headings): */
	print_table(lower, upper, step);
	
	return 0;
}
/* END OF MAIN PROGRAM */


/* FUNCTION TO CONVERT FAHRENHEIT TO CELSIUS */
double celsius_of(int fahr)
{
	return (static_cast<double>(5)/9) * (fahr - 32);
}
/* END OF FUNCTION */
	

/* FUNCTION TO CONVERT FAHRENHEIT TO ABSOLUTE VALUE */
double absolute_value_of(int fahr)
{
	return ((static_cast<double>(5)/9) * (fahr - 32)) + 273.15;
}
/* END OF FUNCTION */
	

/* START OF FUNCTION */
void print_preliminary_message()
{
	cout << "This program prints out a conversion table of temperatures." << endl << endl;
}
/* END OF FUNCTION */	
	

/* START OF FUNCTION */
void input_table_specifications(int& lowest_entry, int& highest_entry, int& step_size)
{
	cout << "Enter the minimum (whole number) temperature" << endl;
	cout << "you want in the table, in Fahrenheit: ";
	cin >> lowest_entry;
	cout << "Enter the maximum temperature you want in the table: ";
	cin >> highest_entry;
	cout << "Enter the temperature difference you want between table entries: ";
	cin >> step_size;
	cout << endl << endl;
}
/* END OF FUNCTION */
	

/* START OF FUNCTION */
void print_message_echoing_input(int lowest_entry, int highest_entry, int step_size)
{
	cout << "Tempertature conversion table from " << lowest_entry << " Fahrenheit" << endl;
	cout << "to " << highest_entry << " Fahrenheit, in steps of ";
	cout << step_size << " Fahrenheit:" << endl << endl;
}
/* END OF FUNCTION */
	

/* START OF FUNCTION */
void print_table(int lowest_entry, int highest_entry, int step_size)
{
	int fahr; 

	/* Print table heading */
	cout.width(17);
	cout << "Fahrenheit";
	cout.width(13);
	cout << "Celsius" << "Absolute Value" << endl << endl;

	/* set format of individual values */
	cout.precision(2); 
	cout.setf(ios::fixed); 

	/* print table from lowest_entry to highest_entry */
	for (fahr = lowest_entry ; fahr <= highest_entry ; fahr += step_size) {
		cout << "   ";
		cout.width(15);
		cout << fahr;
		cout.width(15);
		cout << celsius_of(fahr) << absolute_value_of(fahr) << endl;
	}
}
/* END OF FUNCTION	*/