Thread: Question involving using math operations...

Alright, I had posted a while ago about a project asigned to us by a teacher involving payrolls and everything. Well, I ditched the whole way we were doing it and started over with something that I hope will work better and it won't open all the files at once. Well, here's my question, I would like to multiply two values in 2 seperate files and have it displayed in another statement. I tried something simple:

Code:

ammount=buffer*5+buffer2;
printf("The total ammount of money owed to Matt is %i.\n",ammount);

buffer and buffer2 are the variables where the numbers in the files are stored. I was wondering why this won't work and if there might be a better way to do it (personally, I don't like to use the printf statement, as it looks sloppy to me). I get an error that says:

error C2296: '*' : bad left operand

I'm just wondering, thanx...

yup.. I have them defined as an int and charters. uuuummm... I'll post the code I have so far for that section. Maybe it's something in the code that's doing it...

Code:

int mattbview()
{
  char buffer[256];
  char buffer2[256];
  int ammount;
  ifstream mattb ("files/mattb.txt");
  ifstream mattb2 ("files/mattb2.txt");
  if (! mattb.is_open() && mattb2.is_open())
  { 
	  cout << "Error opening file"; 
	  EXIT 
  }

  while (! mattb.eof() )
  {
    mattb.getline (buffer,100);
	mattb2.getline (buffer2,100);
	cout << endl << "Name:  Matt Bilcliff";
	cout << endl << "Pay $5/hour";
	cout << endl << "Matt has worked "; 
    cout << buffer;
	cout << " hours.";
	cout << endl << "The boss has given a bonus of ";
	cout << buffer2;
	cout << " dollars";
	ammount = buffer * 5 + buffer2;
	printf("The total ammount of money owed to Matt is %i.\n",ammount);
	mattb.close();
	mattb2.close();
  }
  return 0;
}

Yes, it's not the cleanest mess of anything, but it's a start for now. I'll slim it down and try different things out later. lol.. Noticed that I like the cout to display the text?

Try this:
Leave buffer and buffer2 as char arrays, and change this:
ammount = buffer * 5 + buffer2;

to this:
ammount = atoi(buffer) * 5 + atoi(buffer2);

Function atoi() is in <stdlib.h>.

Originally posted by swoopy
Try this:
Leave buffer and buffer2 as char arrays, and change this:
ammount = buffer * 5 + buffer2;

to this:
ammount = atoi(buffer) * 5 + atoi(buffer2);

Function atoi() is in <stdlib.h>.

Thanks a lot. It worked perfectly. Now I gotta figure out how to stop the text from repeating. I recieve the following:

Name: Mat Bilcliff
Rate: $5/hour
Matt has worked 12 hours
The total ammount of money owed to Matt is 72.
The boss has given a bonus of 12 dollars.
Name: Mat Bilcliff
Rate: $5/hour
Matt has worked hours.
The total ammount of money owed to Matt is 0.
The boss has given a bonus of dollars

uuummm... It seems the bonus is out of order too. uuuummmm... I think it maybe a loop screwed up somewhere.