Question about classes and structures.

I am making the base values for the stats for each race in my text base rpg. Right now I have a stucture set up for it, which I though would be able to house all the information. Either I do not understand how class's and structures work or its not meant to do what I am wanting it to do. Here is what I have so far:

Code:

struct RaceStats { int h_basehp; int h_basemp; int h_basestr; // h = human int h_baseagi; int h_basearmor; int e_basehp; int e_basemp; // e = enchanter int e_basestr; int e_baseagi; int e_basearmor; int b_basehp; int b_basemp; // b = brute int b_basestr; int b_baseagi; int b_basearmor; };

I found out that I can not initialize the values of these variables from inside the structure without getting an error. I tried this

Code:

struct RaceStats { int h_basehp = 200; }

and it gives me an error.
ISO C++ forbids initialization of member `h_basehp'
So I assume either I am doing it wrong or you just cant initialize values from inside the structure. Which would defeat the whole purpose of me using a structure.

Im I just doing it wrong or would it be better to just make these in the global scope and give them values like this?

Code:

#include <iostream> using namespace std; int h_basehp = 200; int main { //code here }

It wouldn't make sense to do so. You could want different initial values for each instance.

You can stuff your initializations in a constructor's [i]initializer list[/i[, though.

Code:

struct RaceStats { RaceStats() : h_basehp(200), h_basearmor(100), ... etc ... { } // more stuff ... };

Cheers

In MY text-based rpg (unfinished, but playable), I define the struct and declare instances of the struct globally, then in the function that creates a character, it saves values to an instance of the struct depending on the class you chose. Here's my code...

Code:

struct statistics { string nam; //Name int lev; //Level int att; //Attack int def; //Defense int tempdef; //To heighten defense for a turn. int agi; //Agility (not currrently used in the program) int mon; //Money int sta; //Stamina int tempsta; //To keep track of player health while regenerating it after battle. float gloc; //To keep track of your location in Story Mode. float exp; //Experience (for leveling up, not currently used) }; statistics player; //For players stats statistics opponent; //For enemy stats during battle

And my createdata() function:

Code:

void createdata(string rac) { if (rac == "d" || rac == "D") { string dnam; ofstream char1("dnam.txt"); //Name ofstream char2("dlev.txt"); //Level ofstream char3("datt.txt"); //Attack ofstream char4("ddef.txt"); //Defense ofstream char5("dagi.txt"); //Agility ofstream char6("dmon.txt"); //Money ofstream char7("dexp.txt"); //Experience ofstream char8("dsta.txt"); //Stamina ofstream char9("dtst.txt"); //Stamina for use in battles; //refills to value of sta after battle(). ofstream char10("dglo.txt"); //See gloc in struct statistics. cout << endl << "What is your character's name? "; cin >> dnam; char1 << dnam; char2 << "1"; //Starting level char3 << "100"; //Starting attack char4 << "95"; //Starting defense char5 << "100"; //Starting agility char6 << "0"; //Starting money char7 << "1"; //Starting experience char8 << "25"; //Starting stamina char10 << "1"; //Starting game loc char1.close(); char2.close(); char3.close(); char4.close(); char5.close(); char6.close(); char7.close(); } else if (rac == "e" || rac == "E") { string enam; ofstream char1("enam.txt"); //Name ofstream char2("elev.txt"); //Level ofstream char3("eatt.txt"); //Attack ofstream char4("edef.txt"); //Defense ofstream char5("eagi.txt"); //Agility ofstream char6("emon.txt"); //Money ofstream char7("eexp.txt"); //Experience ofstream char8("esta.txt"); //Stamina ofstream char9("etst.txt"); //Stamina for use in battles; //refills to value of sta after battle(). ofstream char10("eglo.txt"); //See gloc in struct statistics. cout << endl << "What is your character's name? "; cin >> enam; char1 << enam; char2 << "1"; //Starting level char3 << "50"; //Starting attack char4 << "40"; //Starting defense char5 << "65"; //Starting agility char6 << "0"; //Starting money char7 << "1"; //Starting experience char8 << "20"; //Starting stamina char10 << "1"; //Starting game loc char1.close(); char2.close(); char3.close(); char4.close(); char5.close(); char6.close(); char7.close(); } else if (rac == "h" || rac == "H") { //... //You get the idea.

linkofazeroth, about your createdata function it looks like you are sending each individual statistic to its own file....I may be wrong but thats what it looks like to me. Wouldn't it be better to send all that information to the same file? The reason I ask is because I am working with a 'profile.txt' file that I want to send all the stats for the player to that one specific file. Is there any benifits for sending each stat to its own file or am I misunderstanding the code you wrote for that function?

Quote:

Originally Posted by linkofazeroth

In MY text-based rpg (unfinished, but playable), I define the struct and declare instances of the struct globally, then in the function that creates a character, it saves values to an instance of the struct depending on the class you chose. Here's my code...

Code:

struct statistics { string nam; //Name int lev; //Level int att; //Attack int def; //Defense int tempdef; //To heighten defense for a turn. int agi; //Agility (not currrently used in the program) int mon; //Money int sta; //Stamina int tempsta; //To keep track of player health while regenerating it after battle. float gloc; //To keep track of your location in Story Mode. float exp; //Experience (for leveling up, not currently used) }; statistics player; //For players stats statistics opponent; //For enemy stats during battle

And my createdata() function:

Code:

void createdata(string rac) { if (rac == "d" || rac == "D") { string dnam; ofstream char1("dnam.txt"); //Name ofstream char2("dlev.txt"); //Level ofstream char3("datt.txt"); //Attack ofstream char4("ddef.txt"); //Defense ofstream char5("dagi.txt"); //Agility ofstream char6("dmon.txt"); //Money ofstream char7("dexp.txt"); //Experience ofstream char8("dsta.txt"); //Stamina ofstream char9("dtst.txt"); //Stamina for use in battles; //refills to value of sta after battle(). ofstream char10("dglo.txt"); //See gloc in struct statistics. cout << endl << "What is your character's name? "; cin >> dnam; char1 << dnam; char2 << "1"; //Starting level char3 << "100"; //Starting attack char4 << "95"; //Starting defense char5 << "100"; //Starting agility char6 << "0"; //Starting money char7 << "1"; //Starting experience char8 << "25"; //Starting stamina char10 << "1"; //Starting game loc char1.close(); char2.close(); char3.close(); char4.close(); char5.close(); char6.close(); char7.close(); } else if (rac == "e" || rac == "E") { string enam; ofstream char1("enam.txt"); //Name ofstream char2("elev.txt"); //Level ofstream char3("eatt.txt"); //Attack ofstream char4("edef.txt"); //Defense ofstream char5("eagi.txt"); //Agility ofstream char6("emon.txt"); //Money ofstream char7("eexp.txt"); //Experience ofstream char8("esta.txt"); //Stamina ofstream char9("etst.txt"); //Stamina for use in battles; //refills to value of sta after battle(). ofstream char10("eglo.txt"); //See gloc in struct statistics. cout << endl << "What is your character's name? "; cin >> enam; char1 << enam; char2 << "1"; //Starting level char3 << "50"; //Starting attack char4 << "40"; //Starting defense char5 << "65"; //Starting agility char6 << "0"; //Starting money char7 << "1"; //Starting experience char8 << "20"; //Starting stamina char10 << "1"; //Starting game loc char1.close(); char2.close(); char3.close(); char4.close(); char5.close(); char6.close(); char7.close(); } else if (rac == "h" || rac == "H") { //... //You get the idea.

Considering it would be unwise to read the file containing the data every time you wanted to find out how much health the player had, I would make sure if you did it how linkofazeroth does it.. to do it the way Zach L. does it also, and then pass the variables to write to the file, and not just '20'.

Code:

struct RaceStats { int h_basehp; int h_baselvl; int h_basemp; int h_basestr; // h = human int h_baseagi; int h_basearmor; int e_basehp; int e_baselvl; int e_basemp; // e = enchanter int e_basestr; int e_baseagi; int e_basearmor; RaceStats() : h_basehp(200), h_basearmor(100), ... etc ... { } // more stuff ... } Player, Enemy; void createdata(string rac) { if (rac == "d" || rac == "D") { string dnam; ofstream char1("dnam.txt"); //Name ofstream char2("dlev.txt"); //Level ofstream char3("datt.txt"); //Attack ofstream char4("ddef.txt"); //Defense ofstream char5("dagi.txt"); //Agility ofstream char6("dmon.txt"); //Money ofstream char7("dexp.txt"); //Experience ofstream char8("dsta.txt"); //Stamina ofstream char9("dtst.txt"); //Stamina for use in battles; //refills to value of sta after battle(). ofstream char10("dglo.txt"); //See gloc in struct statistics. cout << endl << "What is your character's name? "; cin >> dnam; char1 << dnam; char2 << Player.h_baselvl; //Starting level char3 << Player.h_baseatk; //Starting attack char4 << Player.h_basedef; //Starting defense char5 << Player.h_baseagi; //Starting agility char6 << Player.h_basemon; //Starting money char7 << Player.h_baseexp; //Starting experience char8 << Player.h_basesta; //Starting stamina char10 << Player.h_baseloc; //Starting game loc char1.close(); char2.close(); char3.close(); char4.close(); char5.close(); char6.close(); char7.close(); } else if (rac == "e" || rac == "E")

I would also consider using classes for the player data, instead of a struct. Have one class be Race, then derive the different type of races from that, 'class Elf : public Race {};'. That way any similar starting variables (ie. baseloc //location) that all races share can be in the Race class, and the others that differ can overload in the derived Elf/Human/etc. classes.

Just ideas, if you dont understand just ignore me.

No, you understood it right. I don't know how to make the program search in a file for a certain value and pull it up (I have a function called load()), so I'm stuck with separate files. Like, if I have a file that looks like this...

Code:

1 5 5 4 6 0 0 1

...I can't (or don't know how to) make the program search for a specific number. Maybe if I could tell a function to look at a certain line in the file and pull that line's value out, that'd be helpful, but I don't know how.

Did my previous post help you with your problem at all, though?

Quote:

Originally Posted by linkofazeroth

Did my previous post help you with your problem at all, though?

Not really, but your sturct statistics(); function was nice and will help me to shorten my code in the long run. It's a nice structure that I will probably use, and modify a bit, to help create random encounter mobs. :D

I think I am gonna stick with the initializer list that Zach L. posted.

I created my own function for that, too, called monst(). It's incomplete, buuut...
(Oh, and struct statistics isn't a function, it's a struct. Similar to a class, actually.)

Code:

void monst() { int rando = 1+rand()%50; if (player.lev >= 1 && player.lev <= 3) { if (rando <= 5 && rando >= 0) { opponent.nam = "Bug"; opponent.lev = 1; opponent.att = 3; opponent.def = 2; opponent.agi = 2; opponent.mon = 10; opponent.sta = 10; opponent.exp = 5; } else if (rando > 5) { opponent.nam = "Rabbit"; opponent.lev = 1; opponent.att = 3; opponent.def = 3; opponent.agi = 3; opponent.mon = 5; opponent.sta = 15; opponent.exp = 10; } } }

Quote:

Originally Posted by Dae

Considering it would be unwise to read the file containing the data every time you wanted to find out how much health the player had, I would make sure if you did it how linkofazeroth does it.. to do it the way Zach L. does it also, and then pass the variables to write to the file, and not just '20'.

Why would it be unwise to read the file every time you wanted to pull information from it?

Mostly it's memory usage (I think. I'm not too knowledgable on that subject). Keeping an ifstream open, or repeatedly closing and opening one, could potentially use more memory than you want.

I wrote a program with lots of hard-coded information. The executable was about 30KB. Then I removed the info and read it in from a file. The exe was 16KB. There is no loss in speed, and some gain in flexibility.

Quote:

Originally Posted by dwks

I wrote a program with lots of hard-coded information. The executable was about 30KB. Then I removed the info and read it in from a file. The exe was 16KB. There is no loss in speed, and some gain in flexibility.

I'm unable to decipher what the point is. Do you mean reading in from files and leaving the ifstream open is good, or that it's better to use the ifstream quickly (like you open, use, then close)?

Thank you to all who posted, I think I have it working the way I want to now.

Just saying that I like to read information in from a file. You can leave the stream open or close it, I don't think it would make too much difference. Unless another program is using the same file or something.

No difference from reading from say a struct, or loading a struct from a file and using it? I'll keep that in mind and check that out, that would be nice. But I would assume the stream and functions going on in the background cause some slow effect.

Geez, Dae, you take meanings from my posts I never even knew were there...

Quote:

Originally Posted by linkofazeroth

No, you understood it right. I don't know how to make the program search in a file for a certain value and pull it up (I have a function called load()), so I'm stuck with separate files. Like, if I have a file that looks like this...

Code:

1 5 5 4 6 0 0 1

...I can't (or don't know how to) make the program search for a specific number. Maybe if I could tell a function to look at a certain line in the file and pull that line's value out, that'd be helpful, but I don't know how.

Did my previous post help you with your problem at all, though?

I've been doing it like this:

Code:

#include <iostream> #include <fstream> class Human { private: int m_minHealth; int m_maxHealth; int m_minMana; int m_maxMana; int m_minStamina; int m_maxStamina; public: Human (); int GetMinHealth () { return m_minHealth; } void SetMinHealth (int p_minHealth) { m_minHealth = p_minHealth; } bool Save (const char*); bool Read (const char*); }; Human::Human() : m_minHealth(100), m_maxHealth(100), m_minMana(50), m_maxMana(50), m_minStamina(75), m_maxStamina(75) { } bool Human::Save (const char* p_filename) { int index; FILE* saveFile = fopen (p_filename, "wb"); if (saveFile == 0) return false; fseek (saveFile, 0, SEEK_SET); fwrite (&(m_minHealth), sizeof (m_minHealth), 1, saveFile); fseek (saveFile, sizeof (m_minHealth), SEEK_SET); fwrite (&(m_minHealth), sizeof (m_maxHealth), 1, saveFile); fseek (saveFile, ((sizeof (m_minHealth)) + (sizeof (m_maxHealth))), SEEK_SET); fwrite (&(m_minMana), sizeof (m_minMana), 1, saveFile); fseek (saveFile, ((sizeof (m_minHealth)) + (sizeof (m_maxHealth)) + (sizeof (m_minMana))), SEEK_SET); fwrite (&(m_maxMana), sizeof (m_maxMana), 1, saveFile); fseek (saveFile, ((sizeof (m_minHealth)) + (sizeof (m_maxHealth)) + (sizeof (m_minMana)) + (sizeof (m_maxMana))), SEEK_SET); fwrite (&(m_minStamina), sizeof (m_minStamina), 1, saveFile); fseek (saveFile, ((sizeof (m_minHealth)) + (sizeof (m_maxHealth)) + (sizeof (m_minMana)) + (sizeof (m_maxMana)) + (sizeof (m_minStamina))), SEEK_SET); fwrite (&(m_maxStamina), sizeof (m_maxStamina), 1, saveFile); fclose (saveFile); //if (written != m_size) // return false; return true; } bool Human::Read (const char* p_filename) { int read = 0; FILE* infile = fopen (p_filename, "rb"); if (infile == 0) return false; read = fread (this, sizeof(int), 6, infile); fclose (infile); //if (read != m_size) // return false; return true; } int main () { Human Hum1; std::cout << Hum1.GetMinHealth() << std::endl; Hum1.SetMinHealth(200); Hum1.Save ("player1.dat"); //save as 200 std::cout << Hum1.GetMinHealth() << std::endl; Hum1.SetMinHealth(300); //set to 300 Hum1.Read ("player1.dat"); //changes it back to 200 std::cout << Hum1.GetMinHealth() << std::endl; //output 200 std::cin.get(); }

The Save and Read methods use ol' C. The Save method shows how to seek to a certain spot (by how many bytes into the file you want to read, and how many bytes you want to read, ie. bytes 12-16 (m_minMana), or 0-4 (m_minHealth)), and the Read method reads the entire saved class into the class you're in (this).

I'm not sure how to do it the C++ way, or how to seek to a specific variable without searching google and doing some reading. I might actually go do that now, itd be beneficial to know, and cplusplus.com has info on the specific functions.

Dae, do you need <cstdio>?

Oh, never mind . . . .

Quote:

Originally Posted by Dae

I'm not sure how to do it the C++ way, or how to seek to a specific variable without searching google and doing some reading. I might actually go do that now, itd be beneficial to know, and cplusplus.com has info on the specific functions.

Use ifstream/ofstream objects. The read/write methods for those objects are equivalent to the fread/fwrite functions. The seekp/seekg functions can perform the same task as the fseek function.

I myself might go the path of overwriting the stream insertion/extraction operators for the class (<</>>) and end up with something like:

Code:

// Create our Human object Hum1 Human Hum1; // Read from input file into Hum1 Human ifstream input("Player.Txt",ios::in|ios::binary); input >> Hum1; input.close(); // Do stuff with the Hum1 Human // Write out data for Hum1 to the output file ofstream output("Player.Txt",ios::out|ios::binary); output << Hum1; output.close();

Quote:

Originally Posted by hk_mp5kpdw

Use ifstream/ofstream objects. The read/write methods for those objects are equivalent to the fread/fwrite functions. The seekp/seekg functions can perform the same task as the fseek function.

I myself might go the path of overwriting the stream insertion/extraction operators for the class (<</>>) and end up with something like:

Code:

// Create our Human object Hum1 Human Hum1; // Read from input file into Hum1 Human ifstream input("Player.Txt",ios::in|ios::binary); input >> Hum1; input.close(); // Do stuff with the Hum1 Human // Write out data for Hum1 to the output file ofstream output("Player.Txt",ios::out|ios::binary); output << Hum1; output.close();

For the past couple hours I was checking that exact method out, heres the C++ equivalent of what I posted above for the text-adventure saving data style (I used if/else's to make it more versatile, save only health, read only health, read all, etc.):

Code:

bool Human::Save (bool p_minHealth, bool p_maxHealth, bool p_minMana, bool p_maxMana, bool p_minStamina, bool p_maxStamina) { long pos = 0; ofstream saveFile ("player2.dat", ofstream::binary); if (!saveFile) { cerr << "Error: file could not be opened" << endl; exit(1); return false; } if (p_minHealth) saveFile << m_minHealth << "\n"; else saveFile.seekp (pos + sizeof (m_minHealth)); pos = saveFile.tellp(); if (p_maxHealth) saveFile << m_maxHealth << "\n"; else saveFile.seekp (pos + sizeof (m_maxHealth)); pos = saveFile.tellp(); if (p_minMana) saveFile << m_minMana << "\n"; else saveFile.seekp (pos + sizeof (m_minMana)); pos = saveFile.tellp(); if (p_maxMana) saveFile << m_maxMana << "\n"; else saveFile.seekp (pos + sizeof (m_maxMana)); pos = saveFile.tellp(); if (p_minStamina) saveFile << m_minStamina << "\n"; else saveFile.seekp (pos + sizeof (m_minStamina)); pos = saveFile.tellp(); if (p_maxStamina) saveFile << m_maxStamina << "\n"; else saveFile.seekp (pos + sizeof (m_maxStamina)); saveFile.close(); return 1; } bool Human::Read (bool p_minHealth, bool p_maxHealth, bool p_minMana, bool p_maxMana, bool p_minStamina, bool p_maxStamina) { long pos = 0; ifstream readFile ("player2.dat", ofstream::binary); if (!readFile) { cerr << "Error: file could not be opened" << endl; exit(1); return false; } if (p_minHealth) readFile >> m_minHealth; else readFile.seekg (pos + sizeof (m_minHealth)); pos = readFile.tellg(); if (p_maxHealth) readFile >> m_maxHealth; else readFile.seekg (pos + sizeof (m_maxHealth)); pos = readFile.tellg(); if (p_minMana) readFile >> m_minMana; else readFile.seekg (pos + sizeof (m_minMana)); pos = readFile.tellg(); if (p_maxMana) readFile >> m_maxMana; else readFile.seekg (pos + sizeof (m_maxMana)); pos = readFile.tellg(); if (p_minStamina) readFile >> m_minStamina; else readFile.seekg (pos + sizeof (m_minStamina)); pos = readFile.tellg(); if (p_maxStamina) readFile >> m_maxStamina; else readFile.seekg (pos + sizeof (m_maxStamina)); readFile.close(); return 1; } int main () { Human Hum1; std::cout << Hum1.GetMinHealth() << std::endl; Hum1.SetMinHealth(200); Hum1.Save (1, 0, 0, 0, 0, 0); std::cout << Hum1.GetMinHealth() << std::endl; Hum1.SetMinHealth(300); Hum1.Read (1, 0, 0, 0, 0, 0); std::cout << Hum1.GetMinHealth() << std::endl; std::cin.get(); }

I just wonder if all that seeking will make it slower, let alone all that reading/writing (since I think >> and << are formatted also).

I also liked using the C version cause the .dat file was like.. encrypted (maybe it was storing the exe of the struct, and thats what was being imported?), where as in this version its just the value.