Stacks in C++

[aemado]

I am creating a program that takes a specified number of nodes in a stack...from here, certain nodes are to be removed based on criteria within the node. Once these certain nodes are removed, they are to be output to the screen. Then, the remaining nodes are to be output. I have created both push and pop functions, and I also need a "remove" function. The remove function is to remove the top node that meets the criteria, and return its properties using reference parameters.

I am really new to stacks...I understand the functionality of push and pop. However, what I don't get is how I would remove these certain nodes and output them. I assume I need to 'pop' them all...? and from there remove the ones of interest? and push the remaining? I am obviously completely lost. Any suggestions anybody may have would be greatly appreciated. Thanks!!

[Ganon11]

I am creating a program that takes a specified number of nodes in a stack...from here, certain nodes are to be removed based on criteria within the node. Once these certain nodes are removed, they are to be output to the screen. Then, the remaining nodes are to be output. I have created both push and pop functions, and I also need a "remove" function. The remove function is to remove the top node that meets the criteria, and return its properties using reference parameters.

What I interpret is that you are writing a function separate from, but dependent on, the stack class. In other words, you will need to use stacks and stack functions in this function.

So that we can felp you better, can I ask a clarification question?

Let's say each node is an int, and your 'criteria' is that the node must be even. So, we push the following values onto a stack (in this order):

1, 5, 3, 2, 8, 9, 4, 6, 11

Now, in your remove, you want to get the first node that meets the criteria. So you pop, and get 11. 11 isn't odd, so you add that to some other data structure (another stack maybe? or a vector, or a list, or whatever). Then you pop 6. 6 is even, so you output 6 and then discard it. Continuing, you will output 6 4 8 2, and then 11 9 3 5 1. Did I get that?

[aemado]

Yes...sort of. I am writing a function in the stack class. This function has two parameters, passed by reference. As you used the example that I am looking for an even....I am looking for a node that meets a criteria of one of the parameters or the criteria of the other parameter. I want to find the first node in which either of these criteria are met. If it is met, I want to remove it from the stack...and therefore return the parameters for output (as it is passed by reference). I don't believe I have another stack or anything to pass it to...just to remove it from the stack, and output the node contents. I want to process through the stack until, like you said, I find all that meet that criteria...and output. Then, I want to output the remaining contents of the stack. In this remove function I will need a loop...as if none of the criteria are met, the two parameters will output -1. Therefore I will know when the stack processing has completed.

Here is what I am trying to accomplish in the main:

stack.remove(condition, brand);
while( condition != -1)
{
cout<<condition<<brand;
stack.remove(condition, brand);
}
 

I am just really unsure how to implement the remove function. I have created an if/else loop (though I'm not sure this is the right approach)....in which I use if to determine if the top->condition and/or top->brand criteria are met. But in else, I am lost. I think I should create another loop and tmp to move through the stack... and then, if none of the criteria are met, return -1 for both parameters.

Thank you so much for your help.

What I interpret is that you are writing a function separate from, but dependent on, the stack class. In other words, you will need to use stacks and stack functions in this function.

So that we can felp you better, can I ask a clarification question?

Let's say each node is an int, and your 'criteria' is that the node must be even. So, we push the following values onto a stack (in this order):

1, 5, 3, 2, 8, 9, 4, 6, 11

Now, in your remove, you want to get the first node that meets the criteria. So you pop, and get 11. 11 isn't odd, so you add that to some other data structure (another stack maybe? or a vector, or a list, or whatever). Then you pop 6. 6 is even, so you output 6 and then discard it. Continuing, you will output 6 4 8 2, and then 11 9 3 5 1. Did I get that?

[Ganon11]

I am just really unsure how to implement the remove function. I have created an if/else loop (though I'm not sure this is the right approach)....in which I use if to determine if the top->condition and/or top->brand criteria are met. But in else, I am lost. I think I should create another loop and tmp to move through the stack... and then, if none of the criteria are met, return -1 for both parameters.

Have you tried doing this? What worked/didn't work? I should think you'd have to use a loop to access all the elements of the stack.

Now, you face a problem inherent in stacks - you can only access the top element. In order to get any other element, you will have to pop() it off the stack. But, if you don't want to lose that element (i.e. to be output later), you need to put it somewhere else. This is where the 'other data structure' comes in. So, in order to eventually access every element, you need to continually get the top element, pop that element from the stack, perform your check, and (possibly) put this element in a safe place for outputting later.

[weaknessforcats]

Yes, Ganon11, I was thinking that a linked list was needed and not a stack.