C++ Workshop - Project 2 - CPP Workshop

Jeromy Walsh · 2008-05-10T06:12:16

Project 2 – Overview Welcome all to the second project of the C++ Workshop. Continuing with the theme of the first project, we will move along in our journey towards making an RPG similar in style to Dungeons & Dragons. In the first project you created characters, gave them ability scores, and had them fight 1 on 1 in an arena environment. However, RPG’s are much more than combat. They’re also about exploration and discovery, and there’s not much to discover in an arena. So in this project we will be breaking out of the arena. Project 2 – Introduction In graphical video games, as in life, what you can see is only limited by your range of vision and your field of view. Although you may not realize it, your eyes take in vast amounts of information in a microsecond, allowing your brain to identify objects, determine the presence of danger, and to become aware of the weather, atmosphere, and mood – for as far as the eye can see. In pen & paper RPG’s, as in text RPG’s, your awareness is much more restricted. If I (or the Dungeon Master) were to try and describe to you everything the eye could see in one sitting, we’d be reading paragraph after paragraph for days, and you’d never get an opportunity to actually DO something. To make the transition from visual to text environments easier, the world is often broken up into smaller, more manageable chunks called rooms. “Imagine you’re standing on a small hill in an open, circular field of dark green grass. The field stretches in all directions and extends almost as far as you can see. At the edge of the field is a forest, which surrounds you on all sides. You notice that to the north the forest has a small opening, and to the south you hear the sound of flowing water. The wind is cool, the air is dry, and the sky is blue and bright above you.” The above is an example of a description which might be read in a “room.” You’ll notice that in the example, its not really a room at all. In fact, it’s not even inside, but outside in an open field. The reason its referred to as a “room” has more to do with the subdivision of the world and the existence of exits, than with the fact that it emulates an actual physical room. When I say the room has “exits,” I mean that there are paths to follow, directions to head, ways in which you can get from this “room” to the next “room.” In the description above, there are two logical exists, north, and south. If the user were to exit either north or south, they would leave the current room and enter one of the adjoining rooms. So if the example “room” above was an entire field, how big is a room normally? Well, a room is as small as possible, in order to contain all relevant information. You notice in the room above that there was very little content. An open field, trees, and a bit of weather. There were no buildings, obstacles, people, objects, or even distinguishable landscape, other than the hill you were on. So it was quite feasible to absorb all of that information in a single paragraph. Now, imagine trying to describe the entire city of New York. It would be impossible to do in a single paragraph and be able to effectively communicate to the user the weather, the people, dangers, and all the shops and stores that would be possible to explore. It goes without saying that you’d more likely divide the city up into city blocks, with each block being described in a single “room.” Or better yet, imagine you’re inside of a medieval castle. The castle itself is smaller than a New York city block, and definitely smaller than a field as large as the eye can see, but yet, you’d still likely subdivide the castle into dozens of rooms representing the actual rooms and hallways of the castle, because that’s all the eye can see. As well, the zoomed in level of detail necessary to see the books on the shelves, the paintings on the walls, and the furniture in the room requires a much smaller subdivision. Which leads me to the next topic. As you’re exploring a medieval castle or dungeon, you’ll often see things lying around. Things such as furniture, armor, weapons, treasure chests, and even piles or coffers of money. Sometimes these things are merely part of the description – such as the furniture. Other times, however, you need to be able to pick up and interact with the object – such as the weapons, armor, or coffers. These require physical objects which you can take, examine, and put in your inventory. Once in your inventory, you want to be able to open it, equip it, or drop it. This implies that you have an inventory, perhaps a backpack, which, much like the room you’re standing in, is a container for other objects. And finally, different types of rooms allow you to do different things. For example, a room in your house might perhaps just have a bed which allows you to “sleep.” While a room in a bank might allow you to “check” your balance, “deposit” some money, or even “withdraw” some money. Another example might be a shop, which allows you to “List” the inventory, “Purchase”, an item, or even “Sell” something from your inventory. Project 2 – Conceptualization This program is a continuation of the program created in project 1. It will again consist of various menus and submenus, however the menus and submenus will now be different depending upon which room you’re in. The primary functionality will be the ability to move in an out and explore different rooms. Each room will have its own description, exits, and contents – which includes objects and other characters. While in a room you will be able to interact with objects, pick up equipment and put it in your inventory, and fight against the other characters which are in the rooms, much as you did in the arena. If you defeat a character, you may then loot his body in order to take any equipment or coins he may have had on him. Some characters will be non-hostile, meaning that they do not attack you when you enter the same room with them, however some of them WILL BE hostile, and will engage you as soon as you enter, so be prepared. As with before, you may create a character, view your stats, and gain experience and level as before. You no longer automatically gain coins for defeating a character (but you can loot their corpses), and you no longer purchase armor and weapons via the main menu. Now, your character begins with a basic, level 1 set of gear and you must enter weapon, armor, and potion shops in order to purchase new equipment. If you should die while fighting in combat, your body is left on the ground where you fell, and you return to the starting room where you began with a new body. All coins are taken by the character that defeated you (and can later be regained by defeating them), but your equipment is left on your body. To prevent losing all of your coins when defeated in combat, it would be wise to store some of it in a bank while exploring. You can reclaim the items by returning to your body and entering your corpse. Project 2 – General Analysis Use Cases 1. Entering The Game When the user first executes the program they will be shown a main menu similar to that displayed below. When the user makes a choice the screen will be cleared and the user will be shown a new menu or screen depending upon which choice was made. It is important to note that “Enter World” will only be shown if a character has been created. If not, “Create Character” is the only option available. ============================== Main Menu ============================== Menu Options: a. Create Character b. Enter World Q. Quit ============================== Choice: 2. Creating a Character When the user selects the option to create a character they will be shown a menu similar to that shown below. If the user selects “Name Character” they will receive a prompt allowing them to enter a name for the character. If the user selects roll for stats, then he will enter a loop where he can continue to “roll for stats” until he finds a suitable distribution. Returning to the previous menu clears the screen and then once again shows the main menu. 2a. If the user has already created a character by previously entering this submenu then entering the “Create Character” menu additional times should first prompt the user that they have already created a character, and that continuing will result in the removal of the old character to make room for the new. If the user opts to continue to “Create a Character” then the menu below is shown. If they decide NOT to create a new character, they will simply be returned to the main menu and their previously created character will remain. ============================== Create Character ============================== Menu Options: a. Name Character b. Roll for Stats R. Return to previous menu ============================== Choice: 3. Entering the World After the user selects “Enter World” they should be taken to a starting room. This can be any room you like, however it should always be consistent, and should be safe from opposing characters or monsters. Typical choices are a Church/Cathedral, a Town Hall, or an upstairs bedroom in an Inn. When the character is transferred to the starting room is should be treated as entering any room. See Below. 4. Entering a Room When a player enters a room they should be shown a screen similar to that listed below. It should show the title of the room, the long description, the exits, and any objects or characters in the room. After all of those have been shown, a menu will appear which lists the available choices. The menu should be dynamically, with directions for exits, “Examine objects” if there are any objects in the room, “Attack” if there are any other characters in the room, and any shopping or banking options as will be discussed later. Additionally, the “Character” option should be available in all rooms. ============================== The Grassy Hill ============================== You’re standing on a small hill in an open, circular field of dark green grass. The field stretches in all directions and extends almost as far as you can see. At the edge of the field is a forest, which surrounds you on all sides. You notice that to the north the forest has a small opening, and to the south you hear the sound of flowing water. The wind is cool, the air is dry, and the sky is blue and bright above you. Obvious Exits: North, South A small tombstone A broadsword ============================== Menu Options: n. North s. South x. Examine Objects c. Character q. Quit ============================== Choice: 5. Using Exits Using an exit simply transports the user from one room to the appropriate connected room. The screen is cleared and they are shown a new screen appropriate for entering the new room. 6. The Character Screen Whenever the user selects the “Character” screen are they choosing to view the information about their character. The screen should be cleared and they should be shown the View Stats menu from project 1. Additionally, the screen should contain 3 new options – V. View Inventory, E. Equip Items, and R. Return. Selecting either of the first 2 will show them a submenu, select R will return them to the view of the room. 6a. Viewing inventory simply gives the user a numbered list of all items their character is currently holding in their bag. From the Inventory screen the user may select any of the items by number which then prompts the user if they’d like to drop the item. Selecting yes drops the item, selecting no returns the user to the Inventory Menu. Additionally, the user may select ‘r’ for return to character screen. 6b. When the user opts to Equip Items, they should be shown what’s currently equipped (armor & weapons) and they should be shown a numbered list of all items in their inventory which can be equipped. Selecting one of those numbers swaps the item currently equipped with the item they selected. The last 2 numbers should be reserved for “remove weapon” and “remove armor,” just in case they want to remove it without first equipping something else. 7. Examining Objects When the user views a room they are shown a list of items in the room and are also given a menu option to “Examine Objects.” If the user selects that option they are taken to a sub-menu which again lists the items in the room, this time numbered. Selecting a number prints the description of the corresponding object, and also gives the user the option to view contents if the item is a container. Additionally, while viewing the object’s description the user may opt to “take” objects which are equip-able, such as weapons and armor, or small enough to carry such as potions or coins. If the object is a container and the user selects to view its contents, they are shown a sub-menu identical to that shown to “examine objects” with all items within the container numbered, etc…This system of objects within objects, and a menu with numbers to examine and then take objects is recursive, and works until all objects within objects have been examined. 8. Attacking Mobs If the room the user is currently in has other characters (non-hostile) they are shown a menu option called “Attack.” Selecting that item will list the characters in the room so the user may decide which character/monster they would like to attack. Once that has been done, combat begins similar to the way in which it was done in project 1, with one small change. 8a. After each round of combat (after both characters have attacked/defended), the user will be shown their hit points and a menu. The menu will contain three options – Attack, Use Item, and Run! Selecting Attack will cause combat to progress for another round. Selecting “Use Item” will show the user a list of items in his inventory which are “Consumable,” such as potions. Selecting one of those items will cause the user to drink the potion, and then continue with the current round of combat. Drinking a potion counts as the user’s turn for that round, so they will not get an opportunity to attack, but they WILL be attacked. Selecting “Run” will usher the character out of the room, in a random direction. (hope they don’t run into a room with a hostile mob). 8b. Attacking a mob and then running flags that mob as hostile. The next time you enter the room, the enemy will continue their attack, however you automatically gain the initiative and get the first swing. 9. Hostile Mobs Whenever you enter a room with 1 or more hostile characters, you are shown the description, the obvious exits, and the objects in the room just as before, however combat immediately begins just as though the player had chosen a character to attack, however without clearing the screen, If there are more than one hostile characters, use initiative or a random chance to determine which attacks first. The first time you enter a new room which contains hostiles they automatically gain the initiative. Every time after that, however, the player gains the initiative. 10. Dying If the player is killed in combat they “die.” Their body is left in the room as an object and their spirit is moved back to the starting room. While a “ghost” the player may only move between rooms and examine objects. They cannot view their stats, open objects, or engage other characters, either hostile or non-hostile. Additionally they cannot shop or bank. Upon returning to the room where they were killed they are given an additional menu option to “Enter Body.” Doing this brings them back to life, with 10% of their full health. If they were killed by a character which was originally “non-hostile” then the character does not attack. If the character was flagged as “hostile” then they will immediately attack once again. As the player has obviously been in this room before, they get the initiative automatically. (Take this as an opportunity to flee.) 10a. When an enemy kills you, they take all of your coins. You may regain those coins upon defeating them, and then examining and opening the corpse. 11. Banks Banks are special rooms which follow all of the rules above, with the addition of a few new menu choices. In a bank you gain the ability to “Check Balance”, “Deposit”, and “Withdraw.” Selecting “Check balance” prints the amount of money you have in the bank, and then reprints the menu “choice” prompt, without clearing the screen. Selecting either Deposit or Withdraw takes you to a suitable sub-menu, where you are shown the amount you can deposit or withdraw, and then a prompt asking you for how much you’d like to deposit or withdraw, respectively. From any of these menus you may “return” to the bank by using the “Return” menu option. 12. Shops Shops are special rooms which follow all of the rules above, with the addition of a few new menu choices. In a shop you may “List” the items for sale, or you may “Sell” something of your own. Selecting “List” displays a numbered list of items for sale, with the amount and attributes of the items identical to the system used in Project 1. Selecting “Sell” will show you all the items in your inventory, along with the prices being offered by the shop. By default, sell prices are 1 / 4 the purchase price. Project 2 – Conclusion By the time this project is over you should be able to create a character, move around in the world, and either collect objects or engage other characters in combat. This is no small project and I very much look forward to seeing what the members of this workshop can come up with. I’ve made every effort to make the analysis thorough enough that you should be able to come up with a pretty accurate design. However, its always difficult to describe a task to someone when you already have the design and implementation in mind. If there’s anything I was overly vague on, or left too much to doubt, please feel free to ask in this thread. Additionally, please feel free to post any design or implementation questions you have. You may notice that in some places, such as the costs of items, what items there are, and what potions exist that I have not specified anything. This was intentional. Use your imagination. As well, this project description should be viewed as a guideline for testing your skills. It should be treated as a minimum specification. If there’s other things you’d like to add, ideas you have of making the project more enjoyable or interesting, please feel free to post those ideas here on the forum and implement unique features as you see fit. Cheers and good luck!

Zahlman

1,682

October 03, 2006 05:57 AM

Quote:Original post by Deyja
The forums tend to eat anything between less-than and greater-than when they aren't inside source tags. These forums allow html. There's no robust way to distinquish between an html tag and, say, a template parameter list - that's why we have source tags.

Additional notes:

- You can use HTML entity escape sequences, e.g. < becomes <, &rt; becomes &rt and & becomes &.

- APs generally get screwed over on this stuff. Please register (or log in if you've already registered).

JWalsh

498

Author

October 03, 2006 11:03 AM

Quote:Original post by Ceoddyn
I have a question relating to the workshop as a whole - what will happen after we complete the book?

Upon completion of the textbook we'll have 1 more final project. At the end of the project the workshop will be 'completed.'

As for what GameDev plans to do with the Workshop after that, I have no idea. My advice would be to rename the threads based on the chapter contents, ie "Arrays", "Polymorphism", etc....and then just rename the forum from CPP Workshop to "CPP Language" or somesuch. We've got the beginnings of a strong question/answer base here, and I still see quite a few questions on FB about C++. So I think a forum dedicated to the C++ Language, given the language's popularity for game programming, isnt a bad idea.

Cheers!

Jeromy Walsh
Sr. Tools & Engine Programmer | Software Engineer
Microsoft Windows Phone Team
Chronicles of Elyria (An In-development MMORPG)
GameDevelopedia.com - Blog & Tutorials
GDNet Mentoring: XNA Workshop | C# Workshop | C++ Workshop
"The question is not how far, the question is do you possess the constitution, the depth of faith, to go as far as is needed?" - Il Duche, Boondock Saints

westond

122

October 03, 2006 05:51 PM

So im working on creating the data that will comprise the individual cells of my game, and I want to use a spread sheet to fill in that data... export the spread sheet in a probably comma delimeted format so I can then have the game read that file and create all the cell objects for the game. My question is... would it be better to write a program that created the objects ahead of time and store them as a binary file and then just read the objects from the file... or use the coma delimited file and just convert the text to the needed types of input for the object to be created?

The book doesnt really touch upon the former rather than to say when storing a object in a binary file, the types are preserved. It doesnt say how to call those objects at a later time or a different instance of the program.

Zahlman

1,682

October 03, 2006 08:24 PM

First off, no kind of file can do any kind of "preserving of types" intrinsically - the file is *only* a sequence of bytes. The interpretation of those bytes is 100% up to your program.

Next, be careful to distinguish the concept of "a binary/text file" (which implies, but does not dictate, something about what kinds of patterns of bytes the file contains) from reading or writing a file "in binary/text mode". Usually you want to pair the mode to the file type, but there is nothing really forcing that. There is also the concept of using "binary/text I/O operations" (.read()/.write() etc. versus operator<</>>) which is something different yet again.

Next, [OPINION]note that sometimes it makes sense to make a "program that creates the objects ahead of time" in a higher-level language (like Python), in order to prepare it for the core program (which can then be written more simply, though still in C++).[/OPINION] If you just have one CSV file, you need some way to define which kinds of objects are defined in what areas of the file. It's probably a better idea to rearrange things into your own file format which has an explicit *structure*.

Finally, read this.

westond

122

October 04, 2006 01:05 AM

Zalhman, thanks for the article. Helped explain some things.

This is where im at in my concept of reading files to create objects for the game.

If you read the comments in the source you will see my troubles.

I need to distinguish and end of line in a coma delimited file. In hex the end of line shows up as 0D 0A, but that doesnt translate into any text.

Next I need to take one of the vectors (of char) and concatinate the elements and asign that to a string.. while the other vector (of char) I need to concatinate and turn it into an int.

I may also have other errors as some concepts are still scetchy with vectors.

here is the .h (purposely left the .cpp out since its all straight forward)

class Object{public:    void Setid(int id);	int Getid()const;	void Setchar(std::string word);	std::string Getchar() const;private    int itsid;    std::string itsword;};

here is the main.cpp

#include <fstream>#include <string>#include <vector>#include "object.h"using namespace std;int mian(){    vector <Object> Objv*; //pointer to a vector of objects	std::string filename="test.csv";	ifstream fin(filename); // open the file	char ch;	while (fin.get(ch)) // runs till there is no more	{	 for (int i=0;;i++)	 {	   Object newobj=new Object;  //give the obj a throw away name	   Objv->push_back();  //adds to the vector	             // this now reads the file until the end of a line is reached	  while (ch != //end of line) the hex view of the file shows 0D 0A for end of line	  {	  int commaiterator=0;	  vector <std::string> objtext;	  vector <std::string> objid;	  	  while (ch !=',' && commaiterator==0)	  {	   commaiterator=1;	   for (int i=0;;i++)	   {	    objtext=fin.get(ch);	    objtext.push_back();	    }	    if (ch==',')	     {		   objid.pop_back();  // tighten up the vector	     }	   } // until first comma	  	  while (ch !=',' && commaiterator==1)	  {	   commaiterator=2;	   for (int i;;i++)	   {	    objid=fin.get(ch);		objid.push_back();	    if (ch==',')	    {		  objid.pop_back(); //tighten up the vector	    }	   }	  } // until second comma	 	  int idsize;	  int textsize;	  objtext=objtext.size():	  idsize=objid.size():	  std::string newtext;	  int newid;	  for (int i=0; i<textsize; i++)	  {	   newtext=objtext //need someway to collect the vector	  }      for (int i=0; i<idsize; i++)	  {	   newid=objid //need someway to collect the vector	  }		  	  /// how do i turn objint and objtext into something	  // so that i can do this	  Objv->Setchar(newtext);	  Objv->Setid(newid);	  } // end end of line while	 } // end object for	} //end while	fin.close();	std::string word;	int id;	int size=Objv.size();	for (int i=0; i<size; i++)	{	word=Objv.Getchar();	id=Objv.Getid();	cout<<"Its word: "<<word<<" and its id: "<<id<<endl;	}    	cin<<ch; //just a stop break before exiting console	for (int i=0; (Objv->size())<i; i++)	{	  delete Objv;	}	return 0;}

here is the hex for the input file

seg000:00000000  6F 62 6A 31 2C 31 0D 0A  6F 62 6A 32 2C 32 0D 0A  obj1,1  obj2,2seg000:00000010  6F 62 6A 33 2C 33 0D 0A                           obj3,3

Zahlman

1,682

October 04, 2006 02:48 AM

Please see embedded comments. I removed your comments, and cleaned up your formatting a bit too.

#include <fstream>#include <string>#include <vector>#include "object.h"using namespace std;int mian() { // obviously not right ;)  vector<Object> Objv*;  // No reason to make a pointer to a vector. Just make a vector.  // Also, the pointer right now isn't initialized, so trying to use it wouldn't  // work.  std::string filename = "test.csv";  // If you're 'using namespace std;', you don't need std:: there ;)  // Also, you can initialize strings in new style as well:  // string filename("test.csv");  ifstream fin(filename);  // The ifstream constructor requires a const char*, not a std::string; and  // you have to convert explicitly (via .c_str()).  // But here, there is no reason for ANY of that.  // Just do:  // ifstream fin("test.csv"); directly.  char ch;  while (fin.get(ch)) {    for (int i=0;;i++) {      Object newobj = new Object;      // 'new' would dynamically allocate an object, and give you a pointer.      // So you can't initialize an instance like this, only a pointer-to-      // instance. But you don't want dynamic allocation here anyway. To declare      // the 'newobj' and initialize it with the default Object constructor      // (that seems to be what you want), just do:      // Object newobj;      // Yes, it's really that simple. For *class* types, this *will* initialize      // the variable, using the default constructor.      // In particular, do NOT write:      // Object newobj();      // because that would actually be a function declaration.      Objv->push_back();      // You need to say what you're pushing back :)	         // this now reads the file until the end of a line is reached      while (ch != '\n') {        // Just use \n. You opened the file in text mode, which means that        // hex 0d 0a sequence (carriage return and line feed) will be translated        // automatically into a single \n character.	int commaiterator = 0;        // This is badly named.	vector<std::string> objtext;	vector<std::string> objid;	  	while (ch != ',' && commaiterator == 0) {	  commaiterator = 1;	  for (int i=0;;i++) {	    objtext = fin.get(ch);	    objtext.push_back();            // Uh, I think you want to be writing into a string, and then            // push_back'ing the string onto the vector?            // Also, how are you planning to break out of this loop?	  }	  if (ch==',') {            objid.pop_back();            // This does not "tighten up" the vector. If you want to            // shrink the space to fit the elements, use:            vector<string>(objid).swap(objid);            // Except, why are you operating on objid now instead of objtext?          }        } // until first comma	          while (ch != ',' && commaiterator == 1) {	  commaiterator=2;	  for (int i;;i++) { // need to initialize i to 0	    objid=fin.get(ch);            objid.push_back();	    if (ch==',') {              objid.pop_back();              // See above. Also, why is this 'if' inside the 'for' this time,              // but outside the 'for' previously?	    }	  }	} // until second comma	 	int idsize;	int textsize;	objtext=objtext.size(): // should be textsize= ?	idsize=objid.size():        // Should be semicolons instead of colons        // Also, initialize instead	std::string newtext;	int newid;	for (int i=0; i<textsize; i++) {	  newtext=objtext // missing semicolon          // I have no idea what you mean by "collect the vector".	}              for (int i=0; i<idsize; i++) {	  newid=objid // similarly here	}	        Objv->Setchar(newtext);        // Oh, you were looking for a string to number conversion here?        // Use a std::stringstream to do the conversion; examples about around here	Objv->Setid(newid);      } // end end of line while    } // end object for  } //end while  fin.close(); // not necessary  std::string word;  int id;  int size=Objv.size();  for (int i=0; i<size; i++) {    word=Objv.Getchar();    id=Objv.Getid();    cout<<"Its word: "<<word<<" and its id: "<<id<<endl;  }      cin<<ch;  for (int i=0; (Objv->size())<i; i++) {    // No; you made a pointer to a vector, not a vector of pointers.    delete Objv;  }  return 0; // don't need this}

But that said, you're going about things *completely* the wrong way, and the above is pretty much unsalvagable garbage anyway. :(

Notes:

- As indicated in the embedded comments, you basically have a text file, so you should just read in text mode (as you currently do) and don't need to worry about those end-of-line sequences; they will be translated automatically.

- You don't need to iterate character by character. Use std::getline() to read the file up to some value, directly reading strings.

- Don't collect everything into two "parallel" vectors and then try to process the vectors. Instead, create Object instances as you go.

- Give the object a constructor, so that you can do that directly. Use an initializer list. (Do the string-to-int conversion *before* invoking the constructor).

- Don't use those god-awful gets and sets. Please.

It's really a lot easier to do this than you think:

// *** spoilers! ***// This is based off the sample data you provided.// Note that in .csv files, things could actually be much more complex,// in cases where the data is supposed to contain commas and/or quotation marks.// Proper, robust parsing of .csv is *not easy*; you might want to look for// a library for it, in fact.#include <fstream>#include <string>#include <vector>struct Object {  int itsid;  std::string itsword;  Object(int anid, const std::string& aword) : itsid(anid), itsword(aword) {}};using namespace std;int main() {  vector<Object> objects;  ifstream fin("test.csv");  string text;  int id;  // While we are able to consume any leading whitespace (this will also  // skip past the newline left by a previous read if any), read up until a   // comma into text, and subsequently read into a number:  while (fin >> ws && getline(fin, text, ',') && fin >> id ) {    // Create an object with those values and put it in the vector.    objects.push_back(Object(id, text));  }  // display them.  for (int i=0; i < objects.size; ++i) {    Object& o = objects;    cout << "Its word: " << o.itsword << " and its id: " << o.itsid << endl;  }}

westond

122

October 04, 2006 03:44 AM

Quote:Original post by Zahlman
- As indicated in the embedded comments, you basically have a text file, so you should just read in text mode (as you currently do) and don't need to worry about those end-of-line sequences; they will be translated automatically.

Now that I know what the 0A 0D mean that will make it easier for text mode anyway. Im going to have to push this to binary I think since some of the objects will eventually have pointers to other types of objects. But, one step at a time.

I also dont seem to quite understand whats going on here

while (fin >> ws && getline(fin, text, ',') && fin >> id ) {    // Create an object with those values and put it in the vector.    objects.push_back(Object(id, text));  }

I understand the push back statement... thats actually a nice way to do it except did you mean objects(id, text) since that is the reference name you gave the Object. (object was a bad class name.. but made sense to me)

Quote:
- Don't use those god-awful gets and sets. Please.

sorry, havent been at this for very long. I like doing things the long way as it tends to make more logical sense when every step is written out. Ill start to shorten code as I gain more understanding of whats going on.

You said in my source:

Quote:
vector<Object> Objv*;
// No reason to make a pointer to a vector. Just make a vector.
// Also, the pointer right now isn't initialized, so trying to use it wouldn't
// work.

//and

Object newobj = new Object;
// 'new' would dynamically allocate an object, and give you a pointer.
// So you can't initialize an instance like this, only a pointer-to-
// instance. But you don't want dynamic allocation here anyway. To declare
// the 'newobj' and initialize it with the default Object constructor
// (that seems to be what you want), just do:
// Object newobj;
// Yes, it's really that simple. For *class* types, this *will* initialize
// the variable, using the default constructor.
// In particular, do NOT write:
// Object newobj();
// because that would actually be a function declaration.

I like pointers much more than straight reference (right word?) that exist on the stack. With a pointer I know it wont go out of scope and gives me more felxability... not to mention not having to mess with the copy constructor and destructor everytime I manipulate an object. I think what I meant to do was

vector<Object> objvec;*pobjvec=objvec;

The reason I want to dynamically create the object is for the same reasons I want the vecter to be a pointer. In the end these vectors are only temporary holders of the objects. Once the objects are created in the larger project they will contain an x,y coordinate that will map them to a multidimensional array so I can activate objects by array arithmatic. Oh, and I should have done this Object *newobj = new Object;

Please excuse the noobish lingo... but that really is the hardest thing to learn. The rest comes from doing.

RinusMaximus

122

October 04, 2006 05:52 AM

I was thinking about using a more readible format, either XML or some pseudo class declarations, and build some kind of parser to instantiate objects for this. Or maybe instantiate my objects with DOM nodes which contain their starting values.

either:

<room id="1">   <exit room="2"/>   <exit room="3"/>   <exit room="4"/>   <item type="weapon" name="BastardSword"/>   <enemy level="2"/></room>

or:

class Room{   id=1   exit.room=2   exit.room=3   exit.room=4   item.type=weapon   item.name=BastardSword   enemy.level=2}

This way it is easier to design your game. Once you have a problem inside your binary data it is hard to fix.

Darkstrike

206

October 04, 2006 07:15 AM

You're giving away all my ideas! :P

Anyway, I'd like to know how long would this kind of mini-project take for an experienced programmer? It seems to be taking awfully long for me, and the code's getting hard to read way too easily; I've attached the current state of affairs, and while it doesn't have containers and combat in it, the source is already feeling bloated to me.

edit: wee, finally got some time to spare. Containers are in, and you can now manipulate your inventory as well.

edit2: cleaned up the code a bit, and ended up tucking most of the RTTI under "natural" polymorphism :blush:

bloat compiled bloat

[Edited by - Darkstrike on October 29, 2006 4:15:53 AM]

Zahlman

1,682

October 05, 2006 04:05 AM

Quote:Original post by westond
Now that I know what the 0A 0D mean that will make it easier for text mode anyway. Im going to have to push this to binary I think since some of the objects will eventually have pointers to other types of objects. But, one step at a time.

Ouch. Be VERY careful. You CANNOT just write a pointer value into a file and expect it to work when you read it back in. Why? Because even if you used arcane hacks (and believe me, they are arcane) to try to make every object be at the same place in memory as it was in the previous run (in addition to having them merely be "linked up" in the same way), you can't guarantee that all of the same chunks will be *available* to you this time. Instead, you need to write some kind of data that abstractly represents the way the objects pointed at each other before.

Seriously, just read the FAQ chapter (the link above).

Quote:I also dont seem to quite understand whats going on here

It's explained in the comment directly above:

Quote:
// While we are able to consume any leading whitespace (this will also
// skip past the newline left by a previous read if any), read up until a
// comma into text, and subsequently read into a number:
while (fin >> ws && getline(fin, text, ',') && fin >> id ) {

"while (fin >> ws", for example, attempts to do "fin >> ws". This operator actually will always return 'fin' back again. The skipping of any leading whitespace (this is the somewhat magical behaviour of reading into std::ws - it's the same manner of beast as std::endl for example) is done *as a side effect*. Then, since we're in a boolean context, 'fin' evaluates as true if and only if the stream is still "good"; i.e. the operation was successful. Similarly the other stream reads.

More info.

Quote:
I understand the push back statement... thats actually a nice way to do it

It's standard (idiomatic) to add things to a vector that way.

Quote:except did you mean objects(id, text) since that is the reference name you gave the Object. (object was a bad class name.. but made sense to me)

No. Here, 'Object(id, text)' is a constructor call. It creates a temporary Object, and passes it to the push_back. push_back accepts the temporary by const reference (because it's a *const* reference, this will work with a temporary), and copies the Object into the vector. At the end of the statement, the temporary is out of scope, and its destructor (which happens in our case not to do anything) is called.

This is normal and idiomatic use of the language; it's how you get "literals" of object type instead of only having numeric/character/string literals.

Quote:
I like pointers much more than straight reference (right word?) that exist on the stack.

Values.

Quote:With a pointer I know it wont go out of scope and gives me more felxability...

The only flexibility you gain is the flexibility to mess up, add complexity to what you have to write, and add performance overhead. A stack value doesn't go out of scope until the end of the scope you declared it in; if you're having problems, think more about how you scope your variables. Anyway, you *want* to scope your variables as tightly as you possibly can; this is simply a generalization of the standard "globals are bad mm'kay" advice.

Quote:not to mention not having to mess with the copy constructor and destructor everytime I manipulate an object.

Um. I don't have any real idea what you're thinking here. If you're talking about calling a copy constructor or destructor, that's done *automatically by the language*. In fact, it's using extra dynamic allocation that produces extra burden for yourself: you become required to "mess with the destructor" by calling delete (or delete[] as necessary).

If you're talking about *writing* a copy constructor or destructor, then (a) whether or not you *need* one has absolutely, 100% nothing to do with whether you're going to create those objects on the stack or on the heap, and everything to do with dynamically allocated *members of the object*; and (b) the actual process of writing it is again totally independant. An object should not *itself, ever* care whether it is on the heap or on the stack (because it's pretty much impossible for it to *find out* anyway).

Quote:I think what I meant to do was
vector<Object> objvec;
*pobjvec=objvec;

That still doesn't make it a vector-of-pointers-to-Object (which you still don't need). It merely creates the vector-of-Object on the stack, and then copies it to the vector-of-Object that pobjvec is already pointing at. Note that this, in turn, is different from causing pobjvec to point at objvec (you would do that with "pobjvec = &objvec"). Doing things this way (a) requires that pobjvec *already* points at a valid vector-of-Object; (b) overwrites the contents of that vector-of-Object with the contents of objvec.

Quote:The reason I want to dynamically create the object is for the same reasons I want the vecter to be a pointer. In the end these vectors are only temporary holders of the objects. Once the objects are created in the larger project they will contain an x,y coordinate that will map them to a multidimensional array so I can activate objects by array arithmatic. Oh, and I should have done this Object *newobj = new Object;

That's not a reason, and to be honest you're making less and less sense. Please, I'm trying to make this easier for you. Why resist that?

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