My first project

[Caleb]

I've just learned the basics of C++, and as my first real project I am
attempting to construct a text adventure, like back in the good old
days of Commodore 64 BASIC. This is my code so far:

#include <iostream>
#include <string>
using namespace std;

struct room {
int number;
int numofexits;
int special;
string description;
room (int a, int b, int c, string d);

};

room::room (int a, int b, int c, string d) {
number=a;
numofexits=b;
special=c;
description=d;

}

room Foyer(1,3,0,"Yo u are in the foyer of the cathedral.\nIt' s hard to
believe you've just entered for any purpose other than worship
or\nsacrifice.\ n");
room* allrooms[50]={&Foyer};
int location=0;

int main () {
cout << "************** **\n";
cout << "** The Depths **\n";
cout << "************** **\n\n\n";
cout << allrooms[location]->description;

}

Pretty straightforward , I think. My problem is this: Each room is
going to have a number of exits (defined by "numofexits "). Obviously,
those exits will lead to different rooms based on which room you are
standing in. I've tried to make a dynamic array with different sizes
for different objects of the "room" class, but that didn't work out.
What would be the best way to do this? Sorry if I've been confusing in
any way; just point it out and I'll clarify. Thanks in advance for any
help.

[Mensanator]

Caleb wrote:

I've just learned the basics of C++, and as my first real project I am
attempting to construct a text adventure, like back in the good old
days of Commodore 64 BASIC. This is my code so far:

#include <iostream>
#include <string>
using namespace std;

struct room {
int number;
int numofexits;
int special;
string description;
room (int a, int b, int c, string d);

};

room::room (int a, int b, int c, string d) {
number=a;
numofexits=b;
special=c;
description=d;

}

room Foyer(1,3,0,"Yo u are in the foyer of the cathedral.\nIt' s hard to
believe you've just entered for any purpose other than worship
or\nsacrifice.\ n");
room* allrooms[50]={&Foyer};
int location=0;

int main () {
cout << "************** **\n";
cout << "** The Depths **\n";
cout << "************** **\n\n\n";
cout << allrooms[location]->description;

}

Pretty straightforward , I think. My problem is this: Each room is
going to have a number of exits (defined by "numofexits "). Obviously,
those exits will lead to different rooms based on which room you are
standing in. I've tried to make a dynamic array with different sizes
for different objects of the "room" class, but that didn't work out.
What would be the best way to do this? Sorry if I've been confusing in
any way; just point it out and I'll clarify. Thanks in advance for any
help.

I've seen it where there is no "numofexits ". Instead, there are always
the 6 standard exits NSEWUD. This means your room structure doesn't
use dynamic arrays. If a room only uses 3 of the exits, the others are
set to 0 and the program prints "you can't go that way" if the player
tries to take one of those exits. Negative room numbers were used
for special effects such as -99 being GAME OVER.

The extra memory needed to hold six exits for every room as opposed
to holding a variable number of room exits worked well enough on
an Apple ][, so I doubt you'll have a problem with it.

[=?iso-8859-1?q?Erik_Wikstr=F6m?=]

On Dec 20, 6:12 am, "Mensanator " <mensana...@aol .comwrote:

Caleb wrote:

Pretty straightforward , I think. My problem is this: Each room is
going to have a number of exits (defined by "numofexits "). Obviously,
those exits will lead to different rooms based on which room you are
standing in. I've tried to make a dynamic array with different sizes
for different objects of the "room" class, but that didn't work out.
What would be the best way to do this? Sorry if I've been confusing in
any way; just point it out and I'll clarify. Thanks in advance for any
help.

I've seen it where there is no "numofexits ". Instead, there are always
the 6 standard exits NSEWUD. This means your room structure doesn't
use dynamic arrays. If a room only uses 3 of the exits, the others are
set to 0 and the program prints "you can't go that way" if the player
tries to take one of those exits. Negative room numbers were used
for special effects such as -99 being GAME OVER.

The extra memory needed to hold six exits for every room as opposed
to holding a variable number of room exits worked well enough on
an Apple ][, so I doubt you'll have a problem with it.

But it would be so much better C++ to use a vector, else one might
almost as well use C.

--
Erik Wikström

[Michael Ashton]

Caleb wrote:

I've just learned the basics of C++, and as my first real project I am
attempting to construct a text adventure, like back in the good old
days of Commodore 64 BASIC. This is my code so far:

#include <iostream>
#include <string>
using namespace std;

struct room {
int number;
int numofexits;
int special;
string description;
room (int a, int b, int c, string d);

};

room::room (int a, int b, int c, string d) {
number=a;
numofexits=b;
special=c;
description=d;

}

room Foyer(1,3,0,"Yo u are in the foyer of the cathedral.\nIt' s hard to
believe you've just entered for any purpose other than worship
or\nsacrifice.\ n");
room* allrooms[50]={&Foyer};
int location=0;

int main () {
cout << "************** **\n";
cout << "** The Depths **\n";
cout << "************** **\n\n\n";
cout << allrooms[location]->description;

}

Pretty straightforward , I think. My problem is this: Each room is
going to have a number of exits (defined by "numofexits "). Obviously,
those exits will lead to different rooms based on which room you are
standing in. I've tried to make a dynamic array with different sizes
for different objects of the "room" class, but that didn't work out.
What would be the best way to do this? Sorry if I've been confusing in
any way; just point it out and I'll clarify. Thanks in advance for any
help.

Use a list type like vector<>, and put pointers in it; don't put
objects in it directly, by value.

You can't store objects of different sizes in a vector<>. The only way
to do that would be to put objects of different types in the vector,
and you can't do that directly. But you can do it if you put in
pointers of some base class.

So, don't use (for instance) vector<Room-- use vector<Room*ins tead.
Then you can store not only Rooms, but subclasses of Rooms.

The main disadvantage of this scheme is that you must be careful to
delete these pointers when you remove them from the list, because
vector<doesn't do that for you. And things get hairy when you have
Rooms stored in several different lists; that's when reference-counting
begins to look attractive. But that's the price of polymorphism.

(By the way, you might consider using 'class' here instead of 'struct'.
In C++, a struct *is* a class -- the only difference is that its
members are public by default, while the members of a class are private
by default. But most people think 'C-style struct with no methods' when
they see the 'struct' keyword, so a struct with methods and access
specifiers, while perfectly legit, looks odd.)

Good luck! --mpa

[Michael DOUBEZ]

Michael Ashton a écrit :

Caleb wrote:

>I've just learned the basics of C++, and as my first real project I am
attempting to construct a text adventure, like back in the good old
days of Commodore 64 BASIC. This is my code so far:

#include <iostream>
#include <string>
using namespace std;

struct room {
int number;
int numofexits;
int special;
string description;
room (int a, int b, int c, string d);

};

room::room (int a, int b, int c, string d) {
number=a;
numofexits=b;
special=c;
description=d;

}

room Foyer(1,3,0,"Yo u are in the foyer of the cathedral.\nIt' s hard to
believe you've just entered for any purpose other than worship
or\nsacrifice. \n");
room* allrooms[50]={&Foyer};
int location=0;

int main () {
cout << "************** **\n";
cout << "** The Depths **\n";
cout << "************** **\n\n\n";
cout << allrooms[location]->description;

}

Pretty straightforward , I think. My problem is this: Each room is
going to have a number of exits (defined by "numofexits "). Obviously,
those exits will lead to different rooms based on which room you are
standing in. I've tried to make a dynamic array with different sizes
for different objects of the "room" class, but that didn't work out.
What would be the best way to do this? Sorry if I've been confusing in
any way; just point it out and I'll clarify. Thanks in advance for any
help.

Use a list type like vector<>, and put pointers in it; don't put
objects in it directly, by value.
You can't store objects of different sizes in a vector<>. The only way
to do that would be to put objects of different types in the vector,
and you can't do that directly. But you can do it if you put in
pointers of some base class.

So, don't use (for instance) vector<Room-- use vector<Room*ins tead.
Then you can store not only Rooms, but subclasses of Rooms.

The main disadvantage of this scheme is that you must be careful to
delete these pointers when you remove them from the list, because
vector<doesn't do that for you. And things get hairy when you have
Rooms stored in several different lists; that's when reference-counting
begins to look attractive. But that's the price of polymorphism.

When using pointers in this way, Boost's shared_ptr<make s your life
easier with this kind of design:

typedef boost::shared_p tr<RoomRoomShar edPtr
std::vector< RoomSharedPtr allrooms;
....
allrooms.push_b ack(RoomSharedP tr(new room(1,3,0,"You are in the foyer of
the cathedral.\nIt' s hard tobelieve you've just entered for any purpose
other than worship or\nsacrifice.\ n")));

Michael

[Caleb]

Mensanator wrote:

The extra memory needed to hold six exits for every room as opposed
to holding a variable number of room exits worked well enough on
an Apple ][, so I doubt you'll have a problem with it.

Very true. But I had hoped that by learning C++ I could expand the
program into more advanced stuff, such as not being limited to one exit
in each direction. For example, a large room with three evenly-spaced
northward exits that branch into different hallways.

[Caleb]

I will look into this vector business. Thanks for all the suggestions,
and I will report back after I find out about the vector stuff. :)

[Caleb]

std::vector does exactly what I want it to do. It seems to be
extremely advantageous over regular arrays, too. There's just one
thing I'm wondering....is there a way to push_back three elements at
once? For example, I'm going to have a list of door initializations
that look like this:

Foyer.destinati on.push_back(2) ;Foyer.destinat ion.push_back(3 );Foyer.destina tion.push_back( 6);

And that's only for a 3-door room....is there a more efficient way to
code that?

[LR]

Caleb wrote:

Mensanator wrote:

>>The extra memory needed to hold six exits for every room as opposed
to holding a variable number of room exits worked well enough on
an Apple ][, so I doubt you'll have a problem with it.

Very true. But I had hoped that by learning C++ I could expand the
program into more advanced stuff, such as not being limited to one exit
in each direction. For example, a large room with three evenly-spaced
northward exits that branch into different hallways.

How would someone using the program distinguish between those exits? IE
what command would they give that would allow them to go to a particular
exit?

LR

[Caleb]

LR wrote:

How would someone using the program distinguish between those exits? IE
what command would they give that would allow them to go to a particular
exit?

LR

Not that I understand how that's significant to my question, hehe :),
but I'm going to be adding menus of exits/objects in the room to the
room descriptions. If the player wants to move, they'll just input the
number corresponding with the door they want.

I thought of a way I could set it up where I can add multiple elements
with one statement....ra ther simple, really. Just overload an
"add_doors" function with one integer, two integers, five integers, and
whatever amounts of integers that I need, and write it to push_back the
elements that were provided one at a time. Contemplating whether that
would really be worth it, though.