Reverse output for a Stack

siicon · #1 05-Jul-2004, 16:14

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

CPP / C++ / C Code:

#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();
	  };

siicon · #2 05-Jul-2004, 16:26

Hi this is a copy of my prime factorization code before I implement the stack. Once I implement the stack I begin running into errors

CPP / C++ / C Code:

#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;
}

WaltP · #3 06-Jul-2004, 01:04

Quote:

Originally Posted by siicon

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.

Unless I'm not understanding your problem, it's a simple thing.
You have an array with the following values:
[1,2,3,4]
You probably have a variable that has the value 4 (the next empty space in the above array), which I will call nxt. If this is so, then simply:

CPP / C++ / C Code:

for (i=nxt-1; i > 0; i--)
{
    // output this value
}

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Reverse output for a Stack

Prime factor code (by itself)