Guess Number Game

#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;

int main(int argc, char** argv)
{
        system("TITLE Guess My Number.");
        system("COLOR 5");

	srand(static_cast<unsigned int>(time(0)));

	int iMyNumber;
	int iYourNumber;
	int iPoints = 5;
      
	while(true)
	{
		cin.clear();
		iMyNumber = rand() % 100 + 1;
		
		cout << "You start with 5 points, each spin cost 1 point." << endl; 
		cout << "Guess my Number '1 - 100'" << endl;
		cout << "Get as many points as you can!" << endl;
		do
		{
			cout << "Enter your Number ";
			cin >> iYourNumber;
            iPoints += -1;
			if (iYourNumber > iMyNumber)
				cout << "Too high!" << endl << endl;
			else if (iYourNumber < iMyNumber)
				cout << "Too low!" << endl << endl;
		} while (iYourNumber != iMyNumber);
		cout << "Correct!" << endl << endl;
		cout << "You've got " << iPoints << " points." << endl << endl;
		cin.get();
	}
	return 0;
}

iPoints += -1; //Should be iPoints++;

var += -1
or var += 1

var++
var--
++var
--var