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

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

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();
};``````

## All 5 Replies

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;
}``````

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?

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;
}``````

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;
}``````

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;``````
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