help with classes in c++

**backpacking** · Nov 8 '06, 04:09 AM

I see that you posted a while ago. So you might have already found what you are looking for. I was looking at your code and noticed some areas that I might be able to help. I won't be able to help with the graphics, but will get you to a good point so that the code will work easier with a graph control or whatever you find out there that you like. By the way I am going to use generic programming - meaning that this should be able to be used on any platform that there is a c++ compiler for. Here is what we will do.

Encapsulate your example into a class
Optimize the code
Add a couple of events so that people can do whatever they want to with it.

put the following code into the file "Primes.h"

Code:

#ifndef primes
#define primes
#endif

#include "Events.h"

class primeNumbers;

class primeContainer{
    private:
        std::vector<int> cont;
        
        //simple adding method
        void add(int number){
            cont.push_back(number);
            return;
        }

    public:
        primeContainer(){};
        ~primeContainer(){};

        //simple indexing tool
        int operator[](int index){
            std::vector<int>::iterator iter;
            if(index > cont.end()-cont.begin())
                iter = cont.end();
            else
                iter = cont.begin()+index;

            return *iter;
        }
        
        int count(){
            return cont.end()-cont.begin();
        }
        
        friend class primeNumbers;
};

class primeNumbers{
		public:
			EventHandler<void (*)(void*,int)> OnFindPrime;
             
		primeContainer& find(int end){
			primeContainer* pc = new primeContainer();//a container to keep all the primes in and pass
			bool p = true;//marks a number as prime or not
			int limit;//limits the divisor from going above where it needs to - the approximate square root.
			int div;//the divisor

			//loops through all the numbers start through end finding the primes
			for(int current = 2; current <= end; current++){//you would think that you would save skipping even numbers.
				p = true;
				limit = current;
				div = 2;

					//within prime list.  uses the prime list to cut time off of divisions.
				for(int x = 0;x<pc->count() && div<limit;x++){
				    div = pc->operator[](x);
				    limit = current/div;
				    if(current%div == 0){
				        p = false;
				        break;
					}
				} if(p==false)continue;//if the number was found to be false then move on

				//after prime list.  if any other divisors need to be calculated
				for(div;div<limit;div++){//try replacing 'limit' with 'current' to see the time difference
					limit = current/div;//no sense in going above this point
					if(current%div == 0){
						p = false;
						break;
					}
				}

				if(p == true){//if p is still true then it is indeed a prime
					pc->add(current);
					//call events
					for(int x = 0,y = OnFindPrime.size();x<y;x++){
						OnFindPrime[x].function(OnFindPrime[x].caller,current);

					}
				}
			}
			return *pc;
		}
};

//boy did this code get messy. didn't look like that on my computer

now put the following code in a file "Events.h"

Code:

#ifndef events_h
#define events_h
#endif

#include <vector>
using namespace std;

template<typename functionDef>
struct Event{
	functionDef function;//describes a pointer to the described function
	void* caller;
};

template<typename functionDef>
class EventHandler{
	private:
		typedef Event<functionDef> event;
		std::vector<event> container;
		typedef typename vector<event>::iterator iterator;

	public:

		void AddEvent(functionDef function, void* instance = 0){
			event E = {function, instance};
			container.push_back(E);
		}

		void RemoveEvent(functionDef function, void* instance){

			for(iterator current = container.begin(),end = container.end();current<end;current++){
				if(current->function == function && current->caller == instance){
					container.erase(current);
				}
			}
		}

		event& operator[](int index){
			return container[index];
		}

		int size(){
			return container.size();
		}
};

create a static function that looks like the following

Code:

void FoundPrime(void* caller, int currentNumber){
     //do whatever you want to in here
};

use your main() function to test this out - until you see what I did. Make sure that you put the files in the same file that you main() is located. And then include this at the top

Code:

#include "Primes.h"

Code:

primeNumbers pn;
pn.OnFindPrime.AddEvent(FoundPrime, 0);
primeContainer& pc = pn.find(400000);

pn.find returns a container to all the primes from 0 to 400000. But you could add code in your event that pulls out the ones you are looking for. This is a better way for a class to view the problem.

Let me know if this helps. I hope it works on your computer.

**sajenia** · Nov 8 '06, 04:27 PM

Originally posted by backpacking

I see that you posted a while ago. So you might have already found what you are looking for. I was looking at your code and noticed some areas that I might be able to help. I won't be able to help with the graphics, but will get you to a good point so that the code will work easier with a graph control or whatever you find out there that you like. By the way I am going to use generic programming - meaning that this should be able to be used on any platform that there is a c++ compiler for. Here is what we will do.

Encapsulate your example into a class
Optimize the code
Add a couple of events so that people can do whatever they want to with it.

put the following code into the file "Primes.h"

Code:

#ifndef primes
#define primes
#endif

#include "Events.h"

class primeNumbers;

class primeContainer{
    private:
        std::vector<int> cont;
        
        //simple adding method
        void add(int number){
            cont.push_back(number);
            return;
        }

    public:
        primeContainer(){};
        ~primeContainer(){};

        //simple indexing tool
        int operator[](int index){
            std::vector<int>::iterator iter;
            if(index > cont.end()-cont.begin())
                iter = cont.end();
            else
                iter = cont.begin()+index;

            return *iter;
        }
        
        int count(){
            return cont.end()-cont.begin();
        }
        
        friend class primeNumbers;
};

class primeNumbers{
		public:
			EventHandler<void (*)(void*,int)> OnFindPrime;
             
		primeContainer& find(int end){
			primeContainer* pc = new primeContainer();//a container to keep all the primes in and pass
			bool p = true;//marks a number as prime or not
			int limit;//limits the divisor from going above where it needs to - the approximate square root.
			int div;//the divisor

			//loops through all the numbers start through end finding the primes
			for(int current = 2; current <= end; current++){//you would think that you would save skipping even numbers.
				p = true;
				limit = current;
				div = 2;

					//within prime list.  uses the prime list to cut time off of divisions.
				for(int x = 0;x<pc->count() && div<limit;x++){
				    div = pc->operator[](x);
				    limit = current/div;
				    if(current%div == 0){
				        p = false;
				        break;
					}
				} if(p==false)continue;//if the number was found to be false then move on

				//after prime list.  if any other divisors need to be calculated
				for(div;div<limit;div++){//try replacing 'limit' with 'current' to see the time difference
					limit = current/div;//no sense in going above this point
					if(current%div == 0){
						p = false;
						break;
					}
				}

				if(p == true){//if p is still true then it is indeed a prime
					pc->add(current);
					//call events
					for(int x = 0,y = OnFindPrime.size();x<y;x++){
						OnFindPrime[x].function(OnFindPrime[x].caller,current);

					}
				}
			}
			return *pc;
		}
};

//boy did this code get messy. didn't look like that on my computer

now put the following code in a file "Events.h"

Code:

#ifndef events_h
#define events_h
#endif

#include <vector>
using namespace std;

template<typename functionDef>
struct Event{
	functionDef function;//describes a pointer to the described function
	void* caller;
};

template<typename functionDef>
class EventHandler{
	private:
		typedef Event<functionDef> event;
		std::vector<event> container;
		typedef typename vector<event>::iterator iterator;

	public:

		void AddEvent(functionDef function, void* instance = 0){
			event E = {function, instance};
			container.push_back(E);
		}

		void RemoveEvent(functionDef function, void* instance){

			for(iterator current = container.begin(),end = container.end();current<end;current++){
				if(current->function == function && current->caller == instance){
					container.erase(current);
				}
			}
		}

		event& operator[](int index){
			return container[index];
		}

		int size(){
			return container.size();
		}
};

create a static function that looks like the following

Code:

void FoundPrime(void* caller, int currentNumber){
     //do whatever you want to in here
};

use your main() function to test this out - until you see what I did. Make sure that you put the files in the same file that you main() is located. And then include this at the top

Code:

#include "Primes.h"

Code:

primeNumbers pn;
pn.OnFindPrime.AddEvent(FoundPrime, 0);
primeContainer& pc = pn.find(400000);

pn.find returns a container to all the primes from 0 to 400000. But you could add code in your event that pulls out the ones you are looking for. This is a better way for a class to view the problem.

Let me know if this helps. I hope it works on your computer.

thanx, will give the code a try n let u know how it goes on my compiler. thank u!!

help with classes in c++

help with classes in c++

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