Help with Quanity discoundts in C++

[joelw]

First off how do you use tages

Second last night i was getting a warning that quantity wasnt intialized yet so i put quantity = 0 and still came up with 0.00 for the discount. Now, should quantity be 0?

And Third, what do you mean when multiplying doubles by a constant (99), make your constants doubles also?

Thanks in advance

[Paul McKenzie]

First off how do you use tages

Look at the # icon on the message window.

Second last night i was getting a warning that quantity wasnt intialized yet so i put quantity = 0 and still came up with 0.00 for the discount. Now, should quantity be 0?

If quantity is 0, what does the code do? Did you step through the code to see what happens if quantity is 0? The answer is obvious if you take a look at your if() statements.

 if(quantity >= 10 && quantity <= 19)

No.

if(quantity >= 20 && quantity <= 49)

No.

if(quantity >= 50 && quantity <= 99)

No.

if(quantity >= 100)

No.

So what will happen, now that none of those if() statements are true if quantity is 0? It is also confusing that you have variables called "units" and "quantity". What do each of these supposed to denote?

And Third, what do you mean when multiplying doubles by a constant (99), make your constants doubles also?

No.

Regards,

Paul McKenzie

[joelw]

so it should be the other way?

if(quantity <= 10 && quantity >= 19)?

[wildfrog]

so it should be the other way?

if(quantity <= 10 && quantity >= 19)?

Just read that statement out loud and see if it makes sense.

"If quantity is 10 or less, and at the same time 19 or more..."
Will this condition ever be true?

- petter

[wildfrog]

As Paul McKenzie mentioned, why do you use both 'units' and 'quantity'? The user input is placed in 'units', but your if-statements etc. are using 'quantity'.

- petter

[dcjr84]

It is pretty obvious that you are just learning C++, because you are having trouble with some of the most basic concepts of the language. That's ok, but it's honestly in your best interest to solve problems on your own before coming to forums like this to get people to solve your homework problems for you. We are here to help you with problems but that is assuming that you have already written all of your code. Perhaps you are getting some crazy debugging error or runtime issue, things like that.

With that being said, you did make a good attempt at writing your own code once you got a little "nudge" from some of the other members. I think the main problem with the code you wrote is this, as Paul McKenzie pointed out: you didn't cover all of the possible cases for the number of units sold. You didn't account for what will happen if the user enters 0 or a negative number in your program. It probably won't crash, but you will get undefined, and unwanted results. You also had a few syntax errors and some other minor things typical of a person just learning C++, like not indenting within different levels of code. Other than that though, most of it was correct.

I strongly suggest that you do as many more examples of coding as you can, and pay greater attention in class at school. If you are having trouble with if-else statements, you will be in BIG trouble later when you start working with pointers, classes, and polymorphism Good luck.


Parts that are bold are areas I felt you had problems in....

#include<iostream>
#include<iomanip>

using namespace std;

int main()
{

//Initialize variables here
int quantity = 0;
double price = 99.0;
double discounted_price = 0.0;

//Collect input from user
//Should only be ONE variable for input here
//No need for units AND quantity if you only use one of them
cout << "How many units were sold? ";
cin >> quantity;

//Illegal; Negative numbers and zero are not allowed
if ( quantity <= 0 )
{
   cout << "At least one unit must be purchased!" << endl;
   exit(1);
}

//No discount here
if ( quantity >= 1 && quantity <= 10 )
{
   discounted_price = quantity*99;
}

//20% discount here
else if( quantity >= 11 && quantity <= 19 )
{
   discounted_price = quantity*99 - quantity*99*0.2; 
}

//30% discount here
else if( quantity >= 20 && quantity <= 49 )
{
   discounted_price = quantity*99 - quantity*99*0.3; 
}

//40% discount here
else if( quantity >= 50 && quantity <= 99 )
{
   discounted_price = quantity*99 - quantity*99*0.4;
}

//50% discount here
else if( quantity >= 100 )
{
   discounted_price = quantity*99 - quantity*99*0.5;
}

//Display results
cout << fixed << showpoint << setprecision(2);
cout << "The price with the discount is " << discounted_price << endl;

return 0;

}

[Danpiz]

Hey guys, I am doing the same exact problem in my 210 class. The difference is that we have to write the program using pointers. My only question is what is the least number of functions i need to declare?
I declared a function for each quantity level
one for 10-19
one for 20-49
one for 50-99
one for 99-up
and also a function to calc discount.

I am also a noob and I just learned pointers so I am having trouble at finding the most efficient way to declare my functions.

[ariell]

question(s) for you:

a) what to u pay exterminator for writing your code?
b) how about sticking with JavaScript, or so, instead of C?

[ariell]

question(s) for you:

a) what do u pay exterminator for writing your code?
b) how about sticking with JavaScript, or so, instead of C?

[GCDEF]

Hey guys, I am doing the same exact problem in my 210 class. The difference is that we have to write the program using pointers. My only question is what is the least number of functions i need to declare?
I declared a function for each quantity level
one for 10-19
one for 20-49
one for 50-99
one for 99-up
and also a function to calc discount.

I am also a noob and I just learned pointers so I am having trouble at finding the most efficient way to declare my functions.

I don't see how pointers have anything to do with the task at hand. You use pointers when you need them, not just for fun.

The logic seems to be pretty well explained already. You don't need a different calculation for each quantity.

I have no idea what ariell is trying to say.

[Danpiz]

My teacher says that we have to write all our programs using functions and pointers. The code for this problem is provided in our book, but since we are learning pointers, my teacher told us to rewrite the code to our "fashion". I was just wondering what functions I need to declare. There were a couple other students in class that ive seen there code and they all declared a diff # of pointers. So I was wondering whats the easiest way to do it. thanks

[GCDEF]

My response doesn't change. From the first post, I don't see the need for pointers here. "Rewrite the code using pointers" makes no sense.

As to how many functions you need, you start by identifying the logical steps the program has to perform, then dividing them up into functions.

[Danpiz]

if your reponse dosent change from the first post, then dont even bother posting. Sorry, but im not going to tell my teacher his instructions dont make sense. You obviously have bad social behavior beacuse all your post sound like your trying to be a smartass. If you dont like my post or my questions dont respond. There are plenty of C++ forums I have posted on and the so called "Elite" members dont act like you.

[Lindley]

Sorry, but im not going to tell my teacher his instructions dont make sense.

Most teachers are perfectly happy to offer clarification when asked, FYI.

[GCDEF]

if your reponse dosent change from the first post, then dont even bother posting. Sorry, but im not going to tell my teacher his instructions dont make sense. You obviously have bad social behavior beacuse all your post sound like your trying to be a smartass. If you dont like my post or my questions dont respond. There are plenty of C++ forums I have posted on and the so called "Elite" members dont act like you.

Wow. There's a rash of young kids that think they know it all around here lately. Good luck in the real world.

Your question didn't change, why should my response? What do you want us to do when you ask a nonsensical question and then repeat it? You can ask it 30 times, it still won't make sense, and whether you like it or not, my answer is the only possible on you can get at this point.