I’ve made three files using Visual C++ 2008 express for a text based RPG game. Before I really dive into the whole thing I want to get the basics ironed out: new game, save game, continue game, quit game. So far I have the make a character section (in this case find a weapon) and quit game all ironed out. I’m stuck on how to pass the weapon stats from a struct to a save file. I appear to pass the members of the struct without issue and check the file to find “junk”: Ì and -858993460 in place of my values.
How should I go about fixing my save_game and continue_game functions? I’ve done a lot of research trying to figure this out and nothing I’ve tried seems to help.
Here’s the important pieces of the code:
struct player_character
{
char type;
int damage;
int stability;
};
void save_game(player_character& pc, ofstream &save);
void continue_game(player_character& pc, ifstream &get);
int main()
{
player_character pc;
ofstream save;
ifstream get;
//rest of main() goes here.
//pause screen
system("pause");
return 0;
}
//rest of functions go here.
void save_game(player_character &pc, ofstream &save_data)
{
save_data.open ("save.dat", ios::binary);
if (save_data.is_open())
{
save_data << "pc.type = " << pc.type << endl;
save_data << "pc.damage = " << pc.damage << endl;
save_data << "pc.stability = " << pc.stability << endl;
//doesn't work
//save_data.write(reinterpret_cast<char*>(&pc), sizeof(pc));
save_data.close();
}
else
{
cout << " Error. Unable to open file.";
}
}
void continue_game(player_character &pc, ifstream &get_data)
{
get_data.open("save.dat");
if (get_data.is_open())
{
//doesn't work
//get.read(reinterpret_cast<char*>(&pc), sizeof(pc));
get.close();
}
else
{
cout << " Error. Unable to open file.";
}
}
Thanks for the reponse. I’m trying the following revisions. The continue_game function appears to work. I recieve no errors (yet). When I select save after making a character I recieve the following error: Unhandled exception at 0x69197a28 in Undone.exe: 0xC0000005: Access violation reading location 0xffffffcc.
Google shows it as some sort of Windows issue.
Why is my function causing this error?
void save_game(ofstream &save, player_character const &pc)
{
save.open ("save.dat");
if (save.is_open())
{
save.write(reinterpret_cast<char const *>(pc.type), sizeof pc.type);
save.write(reinterpret_cast<char const *>(pc.damage), sizeof pc.damage);
save.write(reinterpret_cast<char const *>(pc.stability), sizeof pc.stability);
save.close();
}
else
{
cout << " Error. Unable to open file.";
}
}
int continue_game(ifstream &get)
{
if (!get.read(reinterpret_cast<char *>(&pc.type), sizeof pc.type)) { /* error */ }
if (!get.read(reinterpret_cast<char *>(&pc.damage), sizeof pc.damage)) { /* error */ }
if (!get.read(reinterpret_cast<char *>(&pc.stability), sizeof pc.stability)) { /* error */ }
return pc.type;
return pc.damage;
return pc.stability;
}
I’ve changed the save_game and continue_game code and included it here. I also collected the debugger and autos output (small version of autos, not all seven pages). Apparently my values are not being evaluated in save_game so continue_game has nothing to work with and doesn’t cause errors.
Here’s the code and debugger/autos printouts:
int save_game(ofstream &save, player_character& pc)
{
save.open ("save.dat", ios::binary);
if (save.is_open())
{
//the error hits here:
save.write(reinterpret_cast<char const *>(pc.type), sizeof pc.type);
save.write(reinterpret_cast<char const *>(pc.damage), sizeof pc.damage);
save.write(reinterpret_cast<char const *>(pc.stability), sizeof pc.stability);
save.close();
}
else
{
cout << " Error. Unable to open file.";
}
return pc.type;
return pc.damage;
return pc.stability;
}
int continue_game(ifstream &get, player_character& pc)
{
get.open ("save.dat", ios::binary);
if (get.is_open())
{
if (!get.read(reinterpret_cast<char *>(&pc.type), sizeof pc.type)) { /* error */ }
if (!get.read(reinterpret_cast<char *>(&pc.damage), sizeof pc.damage)) { /* error */ }
if (!get.read(reinterpret_cast<char *>(&pc.stability), sizeof pc.stability)) { /* error */ }
get.close();
}
else
{
cout << " Error. Unable to open file.";
}
return pc.type;
return pc.damage;
return pc.stability;
}
Debugger Output Window:
First-chance exception at 0x644e7a28 in Undone.exe: 0xC0000005: Access violation reading location 0xffffffcc.
Unhandled exception at 0x644e7a28 in Undone.exe: 0xC0000005: Access violation reading location 0xffffffcc.
Autos:
– pc {type=’Ì’ damage=-858993460 stability=-858993460 } player_character &
type -52 ‘Ì’ char
damage -858993460 int
stability -858993460 int
pc.type -52 ‘Ì’ char
– save {_Filebuffer={…} } std::basic_ofstream > &
+ std::basic_ostream > {…} std::basic_ostream >
+ _Filebuffer {_Pcvt=0x00000000 _Mychar=’Ì’ _Wrotesome=false …} std::basic_filebuf >
Well I’vve managed to make some progress. I discovered I needed to place arguments into my main_menu function (mind you I’m not taking about the main() function, but one I made) so that they would be passed on to my save_game function. I was also able to stop the access error by adding an & into my write function.
So this:
save.write(reinterpret_cast<char const *>(&pc.type), sizeof pc.type);
save.write(reinterpret_cast<char const *>(&pc.damage), sizeof pc.damage);
save.write(reinterpret_cast<char const *>(&pc.stability), sizeof pc.stability);
instead of:
save.write(reinterpret_cast<char const *>(pc.type), sizeof pc.type);
save.write(reinterpret_cast<char const *>(pc.damage), sizeof pc.damage);
save.write(reinterpret_cast<char const *>(pc.stability), sizeof pc.stability);
The savve_game code still doesn’t work properly yet when it comes to putting data into a file but it does printout to the screen.
It looks like I figured it out! Here’s what I’ve come up with: struct in array…and it appears to work just fine.