Reverse Output (Stack)
 

Hi everyone, I've been taking a class on cprogramming and have been successful up thus far. I am now learning about stacks and am having tremendous problems. I've written a program that will calculate the prime factors of numbers. The only problem is that I needed to reverse the output as show in the example below
e.g. Prime factors of #
1
2
3
4

need printout to read
4
3
2
1

I understand the concept in which the output will first be stored in an array [1,2,3,4] but am not entirely sure on how to retreive it without making the program really long. I know about pop functions but have only used this with push empty and full functions in class. I am just having problems on trying to figure out how to implement it here.
I've tested my prime factorization program by itself and I know it works but when I try to integrate it into the stack I get numerous errors and I am not sure if I am on the right track
Please let me know if you have any suggestions. I feel as if I am close but am started to get frustrated because it feels as if I am missing something small
Any help will be greatly appreciated

Thanks in advance
Sean

#include <iostream.h>

const int STACK_MAX= 20;

typedef int StackElement;



class Stack

 {

  private:

   StackElement StackArray[STACK_MAX];

   int StackTop;



 public:

  bool empty();

  int primefactor(int number);

  bool full( );

    bool isprime(int number);

    void push(const StackElement & value);

    void pop();

  int top();

  void display();



    Stack::Stack()                          //Constructor

   {

    StackTop=-1;



   }



  Stack::primefactor(int number)

{

   bool isPrime = isprime();

   int prime = number;

   int i = 2, j;

   double squareroot = sqrt(static_cast<double>(number));

  int count = 0;

   cout << "The prime factorization of the number " << number << " is:" << endl;

  if(isPrime)

      cout << space << number << " is a prime number." << endl;

   else {

      while((prime > 0) && (i <= number)) {

         if((prime % i) == 0) {

        count++;

        for(j = 0; j < count; j++)

          cout << space;

            cout << i << " is a factor" << endl;

            prime /= i;

      } else         

           i++;

      }

 return true;

}





   void Stack::push(const StackElement & value)   //Add value to the Stack

   {

    if(StackTop<STACK_MAX-1)                     //If Stack is not full add element

      {

       ++StackTop;

       StackArray[StackTop]=value;

      }

    else

     cout<<"Stack is full. \n";

   }







  inline bool Stack::empty() const       //Check for emptyness

   {

    return(StackTop==-1);

   }



}



   

    bool isprime(int number)

{

   int i;

   

   for(i = 2; i < number; i++) {

      if((number % i) == 0)

         return false;

   }

   





    StackElement Stack::top()const     //function to retireve value at top of Stack

     {

      if(StackTop>=0)                   //If Stack is not empty perform task

       return StackArray[StackTop];

      else

      cout<<"Stack is empty\n";

      }



     void Stack::pop()         //Function to discard value at top of Stack

      {

       if(StackTop>=0)        //If Stack is not empty perform task

        StackTop--;

       else

       cout<<"Stack is empty\n";

      }



   void Stack::display()     //Function to write the entire stack

    {

     for(int i=StackTop;i>=0;i--)

     cout<<StackArray[i]<<endl;

    }

               

int main()

 {

    Stack factors;

  int number;

   

  cout << "Enter a number > 1000 ";

   cin >> number;



  

   

      factors.primefactor();

      factors.top();

      factors.pop();

      factors.display();

    };

Re: Reverse Output (Stack)
 

This is a copy of my prime number code before implementing the stack

#include <iostream>

#include <string>

#include <cmath>

using namespace std;



const string SPACE_STR = "   ";



void prime_factor(int number);

bool is_prime(int number);



int main() {

   int number;



   cout << "Enter a number > 1000 -> ";

   cin >> number;



   prime_factor(number);



   return 0;

}



// Function I need help with.



void prime_factor(int number)

{

   bool isPrime = is_prime(number);

   int prime = number;

   int i = 2, j;

   double squareRoot = sqrt(static_cast<double>(number));

        int count = 0;

   

   cout << "The prime factorization of the number " << number << " is:" << endl;

        

        if(isPrime)

      cout << SPACE_STR << number << " is a prime number." << endl;

   else {

      while((prime > 0) && (i <= number)) {

         if((prime % i) == 0) {

                                count++;

                                for(j = 0; j < count; j++)

                                        cout << SPACE_STR;

            cout << i << " is a factor" << endl;

            prime /= i;

                        } else         

                 i++;

      }

   }

}



bool is_prime(int number)

{

   int i;

   

   for(i = 2; i < number; i++) {

      if((number % i) == 0)

         return false;

   }

   

   return true;

}

Re: Reverse Output (Stack)
 

Why not just run the original program's loop down from sqrt(number) down to 2, rather than go up? Yes, you'd have to check i with is_prime(), but the numbers would come out in the right order.

If you really want to use a stack, there are standard stack classes, but you could do it without a class very simply too. If it were me, I'd probably do a simple simple simple class:

static const int MAX_STACK = 1000;

class AnIntStack

{

public:

    AnIntStack()    { m_top = 0; }

    void Push(int n) { if (m_top < MAX_STACK) m_stack[m_top++] = n; }

    int Pop(int n) { if (m_top > 0) return m_stack[--m_top]; else return 0; }

    bool IsEmpty() const { return (m_top <= 0); }

protected:

int m_stack[MAX_STACK];

int m_top;

};

and then in your *original* code where you did the output you would say something like mystack.Push(i); and in the main you would have a final loop saying something like "while (!mystack.IsEmpty()) <print element mystack.Pop()>

Is that what you were after?

Re: Reverse Output (Stack)
 

Hello thanks for the tips. I've rewritten most of my code and came up with what's below. I am receiving 3 errors so I am unable to troubleshoot or see if there will be errors in the output. I believe that it is definitely close now. I know that the errors are with my function calls at the end but I thought that this was the method used for calling them.

Example: in the code (w/o stack) if I enter 36 It should return the prime factors
2 is a factor
2 ""
3 ""
3 ""

With the stack implemented now it is supposed to now return
3 is a factor
3 ""
2 ""
2 ""

#include <iostream>

#include <string>

#include <cmath>

using namespace std;



const string SPACE_STR = "   ";



static const int MAX_CAPACITY = 1000;

class Stack

{

public:

    Stack()    { top = 0; }

    void primefactor (int number);

        bool is_prime(int number);

        void Push(int number) ;

    int Pop(int number) ;

  

        

private:

int arraystack[MAX_CAPACITY];

int top;

};



// Function I need help with.



void Stack::primefactor(int number)

{

   bool isPrime = is_prime(number);

   int prime = number;

   int i = 2, j;

   double squareRoot = sqrt(static_cast<double>(number));

        int count = 0;

   

   cout << "The prime factorization of the number " << number << " is:" << endl;

        

        if(isPrime)

      cout << SPACE_STR << number << " is a prime number." << endl;

   else {

      while((prime > 0) && (i <= number)) {

         if((prime % i) == 0) {

                                count++;

                                for(j = 0; j < count; j++)

                                        cout << SPACE_STR;

            cout << i << " is a factor" << endl;

            prime /= i;

                        } else         

                 i++;

      }

   }

}



bool Stack::is_prime (int number)

{

   int i;

   

   for(i = 2; i < number; i++) {

      if((number % i) == 0)

         return false;

   }

   

   return true;

}





void Stack::Push(int number)

{ if (top < MAX_CAPACITY) 

        arraystack[top++] = number; 



}

int Stack::Pop(int number) 

 { if (top > 0) return arraystack[--top]; else return 0; 

 }





int main() {

   int number;



   cout << "Enter a number > 1000 -> ";

   cin >> number;



   Stack::primefactor();

   Stack::Push();

   Stack::Pop();

   return 0;

}

Re: Reverse Output (Stack)
 

Hi, I have completed the code so and am now able to compile but for some reason it will not take the output and reverse it

example prime factors of 100
2
2
5
5

I am still trying to get it to print
5
5
2
2

It seems as if everything is written correctly but the output has not changed :sad:

#include <iostream>

#include <string>

#include <cmath>

using namespace std;



const string SPACE_STR = "   ";



static const int MAX_CAPACITY = 1000;

class Stack

{

public:

    Stack()    { top = 0; }

    void primefactor (int number);

        bool is_prime(int number);

        void Push(int number) ;

    int Pop(int number) ;

  

        

private:

int arraystack[MAX_CAPACITY];

int top;

};



// Function I need help with.



void Stack::primefactor(int number)

{

   bool isPrime = is_prime(number);

   int prime = number;

   int i = 2, j;

   double squareRoot = sqrt(static_cast<double>(number));

        int count = 0;

   

   cout << "The prime factorization of the number " << number << " is:" << endl;

        

        if(isPrime)

      cout << SPACE_STR << number << " is a prime number." << endl;

   else {

      while((prime > 0) && (i <= number)) {

         if((prime % i) == 0) {

                                count++;

                                for(j = 0; j < count; j++)

                                        cout << SPACE_STR;

            cout << i << " is a factor" << endl;

            prime /= i;

                        } else         

                 i++;

      }

   }

}



bool Stack::is_prime (int number)

{

   int i;

   

   for(i = 2; i < number; i++) {

      if((number % i) == 0)

         return false;

   }

   

   return true;

}





void Stack::Push(int number)

{ if (top < MAX_CAPACITY) 

        arraystack[top++] = number; 



}

int Stack::Pop(int number) 

 { if (top > 0) return arraystack[--top]; else return 0; 

 }





int main() {

   Stack mystack;

        int number;



   cout << "Enter a number > 1000 -> ";

   cin >> number;



        mystack.primefactor(number);

        mystack.Push(number);

        mystack.Pop(number);

   



   return 0;

}

Re: Reverse Output (Stack)
 

In your code, where you have:

cout << i << " is a factor" << endl;

That's where you should INSTEAD say:

mystack.Push(i);

So, now it puts things onto the stack instead of printing them. In your main routine, where you now do Push and Pop, you instead need a loop that pops off each pushed number and prints that number out. something like:

int i;

while (i = mystack.Pop())

    cout << i << " is a factor" << endl;