Three Stack array:

[jocdrew21]

I bought this book with different programming idea. I am trying to solve one:

Make a three stack array. Basically push numbers into a stack and when it is full move on to the next stack.

This is what I have so far but on lines 29 and 32 my compiler is saying it is out of bounds which is rather confusing.

#include <iostream>

#define row 10
#define col 2

int stack[row][col];

//place numbers into the first row of array
void push(int num)
{
    
    //check first column if it is full
    for(int i=0; i<row;i++)
    {
        if(stack[i][col-2]==0)
        {
            stack[i][col-2]=num;
            break;
        }
        //checks if first stack is empty and if second stack
        //is empty
        else if(stack[i][col-1]==0 && stack[i][col-2] > 0)
        {
            stack[i][col-1]=num;
            break;
        }
        //checks if first stack is empty and if second stack
        //is empty then check third stack
        else if(stack[i][col]==0 && stack[i][col-2] > 0
                && stack[i][col-1]>0)
        {
            stack[i][col]=num;
            break;
        }
        else
        {
            std::cout<<"ERROR"<<"\n";
        }
    }
}

void pop()
{
    int count=1;
    
    for(int i=0;i<row;i++)
    {
        for(int j=0;j<col;j++)
        {
            if(count==3)
            {
                //makes a line every third iteration
                std::cout<<"\n";
                count=1;//setting count back to 0
            }
            std::cout<<stack[i][j];
        }
        count++;
    }
}
int main(int argc, const char * argv[])
{
    
            for(int i=0;i<30;i++)
            {
                push(i);
            }
            pop();

}

Output:
Error outputs many times before any numbers:
ERROR
ERROR
ERROR
1234
5678
9101112
13141516
17181920

[phantomotap]

O_o

You should start looking into arrays in C. Specifically, you should research how arrays in C are sized/indexed.

That said, you should write a "one stack array" before trying a "three stack array".

Soma

[jocdrew21]

You say I am iterating through the array incorrectly? This is what I am doing with the above code:

//for loop here
stack[iterate rows][static col]; //iterate column one

stack[iterate rows][static col + 1]; //iterate column two

stack[iterate rows][static col + 2]; //iterate column three

I use if statements to check if each column is completely empty, if not the inputed number is placed into that location in the multi array. Once the number is placed a break statement is executed and the loop ends.

[jimblumberg]

//iterate column three

As already pointed out you need to study up a little more on arrays. You created your array with a size of 2 so you only have two columns, not 3. Also in your code you are trying to access your array out of bounds when you use an array index of col. Remember arrays start at zero.

Also why do you assume that zero is the same as an empty Stack? Since this is a C++ program why not make your Stack a class?

Jim

[jocdrew21]

#include <iostream>
#include <stack>
#include <array>

using namespace std;

struct node
{
    stack<int> myStack;
};

class ArrayStack
{
private:
    int count;
    array<node, 3> myArray;
   
public:
    ArrayStack();
    void pushOntoArray(int);
    void popOffArray();
};

ArrayStack::ArrayStack()
{
    count=0;
}

void ArrayStack::pushOntoArray(int num)
{
    node n;
    
    while (n.myStack.size()!=10)
    {
        n.myStack.push(num);
    }
    if (myArray.size()!= 3 && n.myStack.size()==10)
    {
       //jumps out of while loop and assigned node to array
       myArray[count++]=n;
        
        //creates new stack
        n.myStack= *new stack<int>;
        
        //pushes onto new stack
        n.myStack.push(num);
    }
     
}

void ArrayStack::popOffArray()
{
    node n;
    for (int i=0; i<myArray.size(); i++)
    {
        for (int j=0; j<n.myStack.size(); j++)
        {
            int value = myArray[i].myStack.pop();  //here is the error
            
            cout<<value<<"\n";
        }
    }
}

int main(int argc, const char * argv[])
{
    ArrayStack AStack;
    
    for (int i =0; i<30; i++)
    {
        AStack.pushOntoArray(i);
    }
    
    AStack.popOffArray();
    
    return 0;
}

line 61 is the error. I am trying a different approach to the three stack array problem. This one is failing too

[jimblumberg]

If you would bother to read the documentation for std::stack you should see that pop() doesn't return anything, hence the void return type.


Jim

[jocdrew21]

top()

Sorry...

[jocdrew21]

This is odd, now when I debug the program this function is only emplacing 0's?
I am not getting any output from the program?

int main(int argc, const char * argv[])
{
    ArrayStack AStack;
    
    for (int i=0; i<30; i++)
    {
        AStack.pushOntoArray(i);
    }
    
    AStack.popOffArray();
    
    return 0;
}

this is the update to the other code issue

void ArrayStack::popOffArray()
{
    node n;
    for (int i=0; i<myArray.size(); i++)
    {
        for (int j=0; j<n.myStack.size(); j++)
        {
            int value = myArray[i].myStack.top();
            myArray[i].myStack.pop();
            
            cout<<value<<"\n";
        }
    }
}

[Elysia]

You are doing very weird things such as constructing new stacks when there already exists one, assigning to a temporary variable, etc.
Why don't you just do a simple exercise? Push 5 ints to a std::stack, then pop those 5 and print them?
Take it baby steps.

[jocdrew21]

its a question in a book I found. I thought it was tricky and interesting so I thought I would give it a shot.

[Elysia]

Nothing wrong with that, but seeing as you don't seem to grasp how to basic things right, how about doing it in small steps to get the hang of it first?
After that you can put it together to create the complete exercise.

[whiteflags]

its a question in a book I found. I thought it was tricky and interesting so I thought I would give it a shot.

I don't necessarily know what question you are trying to answer or what book it's from. Elysia's advice isn't bad. At the same time, even if you leave, learn about stacks, and come back, I still won't understand what you're really doing.

[jocdrew21]

I understand stacks and it is a programming interview book. The question asked for an array of three stacks. I know there is no real use for the program, I just wanted to see if I could do it.

[whiteflags]

I think you overworked it then. I still don't know what the question is, but std::array<std::stack<int>, 3> is an array of three stacks. The stacks handle ints in this case, but there you go.

[Elysia]

But you still fail to even use the stacks correctly. So again, why not do something simple, get it working and build from there instead of starting from complexity?