#include <stdlib.h>
#include <stdiostream.h>

void main(void)
{
	char	upc[12];
	int		eventotal=0,oddtotal=0,lastnumbertotal=0;
	int		x=0,intcheck=-1;
	
	cout << "Enter a UPC number: ";
	cin >> upc;
	
	cout << endl << endl;
	
	if(strlen(upc)<=10){
		cout << "You entered " << strlen(upc) << " digits." << endl;
		cout << "It isn't enough to do any calculations." << endl;
		exit(0);
	}
	if(strlen(upc)==11){for(x=strlen(upc); x<13; x++){upc[x]='0';}}
	
	//Odd add
	cout << "Odd numbers (positions 1,3,5,etc.): ";
	for(x=0;x<=11;x+=2)
	{
		oddtotal+=(int)upc[x]-48;
		cout << upc[x] << " ";
	}
	cout << endl;
	
	//Even add
	cout << "Even numbers (positions 2,4,6,etc):  ";
	for(x=1;x<=10;x+=2)
	{
		eventotal+=(int)upc[x]-48;
		cout << upc[x] << " ";
	}
	cout << endl << endl;
	
	cout << "The odd number total:	" << oddtotal << endl;
	cout << "The even number total:	" << eventotal << endl << endl;
	
	oddtotal*=3;
	lastnumbertotal=oddtotal+eventotal;
	
	for(x=0; x<10; x++){
		intcheck=(lastnumbertotal+x)/10.0;
		if(intcheck==(lastnumbertotal+x)/10.0){break;}
	}
	
	if((int)upc[11]-48!=0){
		cout << "The entered check digit: " << (int)upc[11]-48 << endl;
		
		cout << "Calculated check digit: " << x << endl << endl;
		
		if((int)upc[11]-48==x){cout << "They are equal! The barcode is good." << endl;} 
		else {cout << "They are not equal. The barcode is bad." << endl;}
	}
	else {
		cout << "The check digit was not entered." << endl;
	
		cout << "Calculated last number of the UPC: " << x << endl << endl;
	}
}