Question

This is about my assignment so I would appreciate generic answers with explanation.

I have a for-loop which I have to make for an online ordering system. The for-loop and ordering all works fine but if the same item is put in twice, then it forgets the previous order for the same item and only remembers the latest one. I am required to use simple arrays and for-loops so I would appreciate if the solution/help was also of this basic level.

My code looks something like this (NOTE: The following is just an example of what part of the loop looks like–this is not a complete program):

for (int i = 0; i < 3; i++) { //I changed the loop so there's no confusion about
                              //what I am actually asking about.
    if (order.equalsIgnoreCase(computer) {
         int price = quantity[i] + itemcode;
    }
}

To explain further, this loop and the if statement work perfectly if a certain item is only ordered once. But if the user enters, say, an order for a computer once and then after 3 more orders, orders another computer, then the output does not add the previous order in the new order but only remembers the latest one.

I would appreciate any work around suggested for this but again, since this is for my studies, I would appreciate explanations rather than direct solutions.

Please ask me questions in case this is not clear.

Answer 1

“Forgets” suggests that you are overwriting something in your code rather than, say, just incrementing. Go through your code, see what parts of it gets reset when you place a new order. For instance, if you are doing

quantity[1] = getNumberFromUser("How many apples?");

then this would obviously erase the old value each time. If you want to merely increment the number of apples, do something like

quantity[1] += getNumberFromUser("How many apples?");

Another general advice is to use print statements to debug your code. That way you can see for yourself what really happens. Learning to use a real debugger would also be of great benefit.