C++ beginner, struggling with parameters

[shellsy]

Hi guys,

I'm working on this problem I've been struggling with for a while now. I'm still confused about parameters and I'm getting all these error messages, saying that a lot of my variables are undefined. I'm sorry, I know this probably looks like a mess right now, but if anyone could help me out as to what I need to change around to get this working, I would be so appreciative.

I'm also not sure if I need the prototypes?

The assignment is in the comments at the top:

// Write a program that can be used to calculate the federal tax. The tax calculated as follows:
// For single people, the standard exemption is $4000; for married people, the standard exemption
// is $7000. A person can also put up to 6% of his or her gross standard income in a pension plan.
// The tax rates are as follows: If the taxable income is
// 1) Between $0 and $15000, the tax rate is 15%
// 2)between $15001 and $40000, the tax is $2250 plus 25% of the taxable income over $15000
// 3)Over $40,000, the tax is $8460 plus 35% of the taxable income over $40000
// Prompt the user to enter the following information:
// 4)Martial status
// 5)If the marital status is "married", ask for the number of children under the age of 14
// 6)Gross salary(if the martial status is "married" and both spouses have income, enter the combined salary.)
// 7) Percentage of gross income contributed to a pension fund.

//The program must consist of at least the following functions:
//a) function getData: this function asks the user to enter the relevant data.
//b) function taxAmount: this function computes and returns the tax owned.

//To calculate the taxable income, subtract the sum of the standard exemption, the amount contributed
//to a pension plan, and the personal exemption, which is $1500 per person.

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

void getData(char marital, int numChild, int& exempt, int& noOfPeople, double& groSalary, double& penAmt);
double taxAmount(double taxIncome, int perExempt, double taxRate);

int main()

{      
	double groSalary;  //variable for gross salary
	double penAmt;     //variable for percent contributed to pension plan
	int exempt;        //variable for standard exemption
	int noOfPeople;    //variable for number of people

    double taxIncome;   //variable for taxable income
	double taxRate;     //variable for federal tax amount owed



	getData(char marital, int numChild, int& exempt, int& noOfPeople, double& groSalary, double& penAmt);
	double taxAmount(double, int, double);

	
	cout << "Your federal tax owed is: " << taxRate << endl;

    return 0;
}	
	
void getData(char marital, int numChild, int& exempt, int& noOfPeople, double& groSalary, double& penAmt)
{

    char marital;      //variable for marital status
    int numChild;      //variable for the number of children under 14
	

	cout << fixed << showpoint;
	cout << setprecision(2);

    cout << "Enter your marital status: 'M' for Married or 'S' for Single: ";
	cin >> marital;
	cout << endl;

	if (marital == 'M' || marital == 'm')
	{
		
		cout << "Enter number of children under the age of 14 years: ";
		cout <<endl;
		cin >> numChild;
		exempt = 7000;
		noOfPeople = 2 + numChild;
	}
	else if (marital == 'S' || marital == 's')
	{		
		exempt = 4000;
        numChild = 0;
		noOfPeople = 1;
	}


	cout << "Enter gross salary. (Enter combined salary for both spouses";
	cout << "if married): ";
	cout << endl; 
	cin >> groSalary;

    cout << "Enter the percentage of your gross income which you have";
	cout << " contributed to a pension fund (Only enter the amount if 6%";
	cout << " or less of your combined gross income: ";
	cout << endl;
	cin >> penAmt;

	if (penAmt > 6)
	{ 
		cout << "You may only enter a percentage which is greater or equal";
		cout << " to 6.  Enter the percentage of your gross income which you have";
		cout << " contributed to a pension fund.  (Only enter the amount if 6%";
		cout << " or less of your combined gross income: ";
		cout << endl;
		cin >> penAmt;
	}

		
	
}

  double taxAmount(double taxRate, int perExempt, int noOfPeople, double taxRate)
{
	double taxRate;  //variable to store taxRate
    double taxAmt;   //variable to store total tax amount
	int perExempt      //variable for personal Exemptions
	

	taxRate = 0;
	
	perExempt = (noOfPeople * 1500) + exempt;
	taxIncome = groSalary - (groSalary * (penAmt * .01)) - perExempt);

	if (taxIncome <= 15000)
	{taxRate = .15 * taxIncome;
	}
	else if (taxIncome > 15000 && taxIncome <= 40000)
	{taxRate = ((taxIncome - 15000) * .25) + 2250;}
	else{
		taxRate = ((taxIncome - 40000) * .35) + 8460;
	}

	return taxRate;
	
	
}

[hacker9801]

I didn't read it all but change the line in main to:

getData(marital, numChild, exempt, noOfPeople, groSalary, penAmt);

Don't put the data-types in the function calls

edit: and you re-declare alot of stuff......

[Duoas]

A parameter is a temporary variable created by your routine. For example:

void bigger_than_five( int number )
{
  result = (number > 5);
}

In this example, number is the parameter (variable).

int main()
{
  if (bigger_than_five( 42 )) std::cout << "42 is bigger than 5\n";
  else std::cout << "hmm... 42 is not bigger than 5 !\n";
}

In this example, 42 is the argument or value we give to the variable 'number'.

The only place that the variable number exists is inside the function bigger_than_five(). Hence, the following is an error:

int main()
{
  number = 42;  // error, 'number' doesn't exist!
  if (bigger_than_five( number )) std::cout << "blah blah blah\n";
}

I hope this helps.

[edit] Yoinks! I'm slow...

[shellsy]

Thanks guys,

I think that helped.

:)

Much appreciated.