//This program uses a free function to calculate the "tax" of an employee
// based on his/her annual salary

//Referncing system files
#include <iostream.h>

//The ouput is formatted thru these two Classes	
#include "textlib.h"
#include "iomanip.h"

//Declaring the Tax Free Function, note that the ";" are replaced by "{ }"
// in the implementation to facilitate compilation.
int calculateTax (int salary);

//Program starts here
int main()
 
{ 
	int  lowest_limit, highest_limit, salaryInc;	
	
	cout<<" Enter the lowest limit of annual"
		  " income you wish to calculate : $";
	cin>> lowest_limit;

	cout<<" Enter the highest limit of annual"
		  " income you wish to calculate: $";
	cin>> highest_limit;
	
	cout<<" Enter the salary incremental"
		  " interval you wish to calculate   : $";
	cin>> salaryInc;

	cout<<endl;
	cout<<endl;


	//Tabulating the output values	
	cout<<"    Salary ($)"<<'\t'
			<<" Tax Amount ($) "
			<<'\t'     
			<<" % Salary taxed  "
			<<endl;

	//Underlining the output values
	cout<<"    __________"<<'\t'
			<<" _______________ "
			<<'\t'     
			<<" ______________  "
			<<endl;	
	
	cout<<endl;


	// Entering the loop in where all the taxes for annual incomes
	// are calculated starting with the lowest bound to the upper bound
	// in such a away that 
	while (salaryInc<=highest_limit)
		{	
			cout<<setw(10)<<salaryInc<<'\t'
			<<'\t'<<calculateTax(salaryInc)
			<<'\t'<<setreal(15,1)
			<<(100*calculateTax(salaryInc)/double (salaryInc))
			<<endl;
			salaryInc+=lowest_limit;
		}
	
	cout<<endl;
	return 0;

}


//The Free function implementation here:
// A free function takes a value, performs computation then return the output
// A free function is similar to a member fuction in its prototype ( returnType,
// functionName and argument list) and doesn't have "Object Name" preceding it!!!
int calculateTax (int salary)

{
	int Tax;

	if (salary<=10000)
		Tax=0;

	else if (salary>10000 && salary<=20000)			
		Tax=(0.2*salary)-2000;

	else if (salary>20000 && salary<=40000)			
		Tax=(0.4*salary)-6000;

	else if (salary>40000 && salary<=60000)		
		Tax=(0.6*salary)-14000;

	else  
		// All the tax ranges are covered up to $60,000
		// so other icomes would definitly fall in this category.
		
		Tax=(0.8*salary)-26000;

	return Tax;

}

//Run: 
/*
 Enter the lowest limit of annual income you wish to calculate : $5000
 Enter the highest limit of annual income you wish to calculate: $100000
 Enter the salary incremental interval you wish to calculate   : $5000


    Salary ($)   Tax Amount ($)          % Salary taxed
    __________   _______________         ______________

      5000              0                   0.0
     10000              0                   0.0
     15000              1000                6.7
     20000              2000               10.0
     25000              4000               16.0
     30000              6000               20.0
     35000              8000               22.9
     40000              10000              25.0
     45000              13000              28.9
     50000              16000              32.0
     55000              19000              34.5
     60000              22000              36.7
     65000              26000              40.0
     70000              30000              42.9
     75000              34000              45.3
     80000              38000              47.5
     85000              42000              49.4
     90000              46000              51.1
     95000              50000              52.6
    100000              54000              54.0

Press any key to continue

*/