confused about functions

[lothrodel]

here is my code, and my problem is how am i gonna display the division name with its sales number, and other thing is how can i be sure that sales are positive? how can i fix these problems. thanks for helping.

#include <iostream>
using namespace std;

double getSales( char division[]);
double findhighest(double, double, double, double);

int main()
{
	double sales1, sales2, sales3, sales4, high;
	char div1[15] = "Southeast"; 
	char div2[15] = "Southwest";
	char div3[15] = "Northeast";
	char div4[15] = "Northwest";
	
	sales1 = getSales(div1);
	sales2 = getSales(div2);
	sales3 = getSales(div3);
	sales4 = getSales(div4);
	cout << "The sales for " << div1 << " are " << sales1 << endl;
	cout << "The sales for " << div2 << " are " << sales2 << endl;
	cout << "The sales for " << div3 << " are " << sales3 << endl;
	cout << "The sales for " << div4 << " are " << sales4 << endl;
	high =  findhighest (sales1, sales2, sales3, sales4);
	cout << "the biggest sale is " << high << endl;
		 
	return 0;
}
double getSales( char division[])
{
	double sales;
	cout << "Get the sales for Division " << division << " ";
	cin >> sales;
	
	return sales;
}
double findhighest(double s1, double s2, double s3, double s4)
{
	
	if (s1 > s2 && s1 > s3 && s1 > s4)
		return s1;
	else if ( s2 > s1 && s2 > s3 && s2 > s4)
		return s2;
	else if ( s3 > s1 && s3 > s2 && s3 > s4)
		return s3;
	else
	    return s4;
	
}