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[TheBiggerFish]

Is there something like Java's BigInteger class you could use?
I don't know if it would help with a stack overflow though...Probably not.


No looping, no operations other than ++ or --.  How would I...

...Store the variables as fields/instance variables, not as method variables?
That way you can at the very least avoid allocating more and more space.

[Reelya]

Well, I finally got around to setting up git, sorta related: you can check out my only war character creator thingy I made here:
https://github.com/Moghjubar/OnlyWarCCreator/blob/master/main.cpp

Pretty much is all console/text and heavily uses selection and while loops, poke around with it if you want 3man75, uses only standard libs.

You have a lot of repeated sections of code there. When you have that, what you should do is make a function, and pass whichever code variations there are into the function as parameters. You could probably cut over half that out without losing any features.

[miauw62]

You could try making several functions that change a and b with larger values to avoid stack overflow. Would probably be pretty messy, though.

[Reelya]

@Avis-Mergulus: Are both numbers you need to sum large? If one is always smaller then swapping them would make it easier. You could also deal with negative b by inverting the process if b<0. Hopefully the following won't cause any infinite loops (due to the b>a and b<0 code which switch around the a and b values)

Code: [Select]

def sum(a, b):
    if(b > a)
        return sum(b, a)
    else if(b < 0)
        return -sum(-a, -b)
    else if(b == 0)
        return a;
    else if(b == 1)
        return a+1
    else
        return sum(a,b)
It all depends on your input numbers. If at least one is close to zero then the above should work fine.

[MagmaMcFry]

Wouldn't negation technically be against the rules?

[TheBiggerFish]

b<0 isn't a case anyway, but I'm sure there could be an if statement just checking and having inverted operations.

[Reelya]

Well looking at similar problems on the web right now, it appears you have to either narrowly specify the allowed operations or the disallowed operations. Otherwise it's not a well-defined problem. For example there are solutions just using bit-wise operations. So we'd have to know if those are specifically disallowed.

[HavingPhun]

So, I am doing a bit of C++ programming, and have run into a problem. I am trying to do something that I thought was possible, but have never done before.

I have this code:

Spoiler: Entity.h (click to show/hide)

Code: [Select]

#include "Files.h"
#include "Tileset.h"

class Entity
{
public:

    Entity(){};
    ~Entity(){};

    bool CanMove;
    bool IsAnimate;
    bool IsLiving;

    int XPosition;
    int YPosition;

    int XWindowPos;
    int YWindowPos;

    int AbsolutePosition;

    int TileID;

    float Velocity = 0;
    int MoveDirection = -1;

    sf::Sprite EntitySprite;

    void UpdateSpritePosition()
    {
        EntitySprite.setPosition(XWindowPos, YWindowPos);
    }

    void SetSprite(int aTileID, Tileset &SpriteTileset)
    {
    TileID = aTileID;

    EntitySprite.setTexture(SpriteTileset.TilesetTexture);
    EntitySprite.setTextureRect(SpriteTileset.GetCellBounds(TileID));
    };
};


Spoiler: Human.h (click to show/hide)

Code: [Select]

#include "Entity.h"
#include "Files.h"

class Human : public Entity
{
    public:
        Human(){};
        ~Human(){};

    bool ReqBreathe = 1;
    bool ReqEat = 1;
    bool ReqDrink = 1;
    bool ReqSleep = 1;

    bool ReqBlood = 1;

    float Health = 100.0;
    float MoveSpeed = 10;
};

Spoiler: Player.h (click to show/hide)

Code: [Select]

#include "Human.h"

class Player : public Human
{
    public:
        Player(){};
        ~Player(){};

    void Configure()
    {
        CanMove = 1;
        IsAnimate = 1;
        IsLiving = 1;
    }
};

Spoiler: EntityManager.h (click to show/hide)

Code: [Select]

#include "Player.h"
#include "Files.h"

class EntityManager
{
    public:
        EntityManager(){};
        ~EntityManager(){};

    std::map <int, Entity> EntityContainer;

    int GetCurrentKey()
    {
        return CurrentKey;
    };
    int GetEntityCount()
    {
        return EntityCount;
    };

    void AddEntity(Entity &NewEntity)
    {
      EntityContainer.insert(std::make_pair(EntityCount, NewEntity));
      CurrentKey++;
      EntityCount++;
    };
    void RemoveEntity(int EntityKey)
    {
        EntityContainer.erase(EntityKey);
        EntityCount++;
    };
    void ClearEntities(int EntityID)
    {
        EntityContainer.clear();
        EntityCount = 0;
    };

    private:
        int EntityCount = 0;
        int CurrentKey = 0;
};


The main area of interest is the declaration of the map "EntityContainer" in EntityManager.h. My thoughts were that since the class "Human" is derived from the class "Entity" and "Player" is derived from "Human", that I would be able to store both of those in the map.

Is there any way to declare a std::map so that it can contain both the class object it is declared to hold and any class object derived from that class?

For example, I try to do something like this:

Code: [Select]

EntityManager EMan;
EMan.AddEntity(new Player);...and receive an error stating that the map was declared to hold "Entity" class objects, not "Player" class objects. What am I doing wrong here?

[MagmaMcFry]

You need to use pointers. Your EntityContainer needs to be a std::map<int, Entity*>, then it will also be able to hold Player*s.

[HavingPhun]

Alright, thanks. So, by using pointers the container can hold anything derived from Entity, correct?

[MagmaMcFry]

Exactly. You can store a Player* in an Entity* variable.

[HavingPhun]

I encountered another problem. Player.h, Human.h, and Entity.h are the same as they were above. Here is the modified code, with an extension to the example which uses it:

Spoiler: EntityManager.h (click to show/hide)

Code: [Select]

#include "Player.h"
#include "Files.h"

class EntityManager
{
    public:
        EntityManager(){};
        ~EntityManager(){};

    std::map <int, Entity*> EntityContainer;

    int GetCurrentKey()
    {
        return CurrentKey;
    };
    int GetEntityCount()
    {
        return EntityCount;
    };

    void AddEntity(Entity* NewEntity)
    {
      EntityContainer.insert(std::make_pair(EntityCount, NewEntity));
      CurrentKey++;
      EntityCount++;
    };
    void RemoveEntity(int EntityKey)
    {
        EntityContainer.erase(EntityKey);
        EntityCount--;
    };
    void ClearEntities(int EntityID)
    {
        EntityContainer.clear();
        EntityCount = 0;
    };

    private:
        int EntityCount = 0;
        int CurrentKey = 0;
};


Spoiler: Example Code (click to show/hide)

Code: [Select]

GenFlatMap();
        PlayerID = EMan.GetCurrentKey();
        EMan.AddEntity(new Player);

        EMan.EntityContainer[PlayerID]->SetSprite(PlayerTileID, CurrentTileset);
        EMan.EntityContainer[PlayerID]->Configure();

        SetPlayerStartPosition(PlayerID);
        UpdatePlayerWindowPos();
        EMan.EntityContainer[PlayerID]->UpdateSpritePosition();

        PlayerView.setCenter(EMan.EntityContainer[PlayerID]->XWindowPos, Eman.EntityContainer[PlayerID->YWindowPos);

        PlayerView.zoom(0.75);

        SetBaseCenterTile();

        CurrentState = InGame;

The "Player" class object is added to the map with no issue. The problem occurs when I try to run a member function of the "Player" object, Configure() on this line:

Code: [Select]

EMan.EntityContainer[PlayerID]->Configure();

Member functions of "Entity" work just fine.

The error being:

Code: [Select]

'class Entity' has no member 'Configure'.
I understand that I could just stick the actions of "Configure" in the constructor of "Player". But, later on the classes derived from "Entity" will have addition member functions which cannot be placed in the constructor. This is one of the things that is out of my area of knowledge, so I am clueless as to what to do.

[Rose]

You have to cast it to player* again before you can use the configure function,  because entity has no such function.
http://en.cppreference.com/w/cpp/language/dynamic_cast

[HavingPhun]

Not to be a pain, but, I still can't figure this out. I read the link which Japa posted and tried several methods, none of which worked, such as:

Code: [Select]

Player* PlayerEntity;
PlayerEntity = dynamic_cast<Player*>(EMan.EntityContainer[PlayerID]);
and:

Code: [Select]

EMan.EntityContainer[PlayerID] = dynamic_cast<Player*>(EMan.EntityContainer[PlayerID]);

...along with dozens of other variations of those. The understanding of this eludes me.

[Rose]

First one is what should be correct. What's the error?