Your vectror::push_back() crashes....

[smartalgorithm]

have you ever experienced program crashes with push_back() function?
how you solved it?
do you know why it happened or when it can happen.
now in my program it crashes, and i can not realize why....
thanks :)

[Disch]

The only ways a push_back would crash is:

1) out of memory (very unlikely)

2) The constructor of the object being copied throws an exception (ie, if you have vector<MyClass>, MyClass's ctor throwing an exception would screw you up if you aren't catching it).

3) Your vector object is bad/corrupt (ie, trying to do somevector->push_back(x); when somevector is a null/bad pointer.

[smartalgorithm]

so if debug shows this:
warning: can't find linker symbol for virtual table for `MyClass' value

what does it mean?
its constructor is very simple:

MyClass::MyClass(std::string name, unsigned short int password, unsigned int money):MyOtherClass(name)
{
  user_password=password;
  user_money=money;
  user_cash=0;
  std::cout<<"hey\n";
}

guess it does not throws exceptions...

[smartalgorithm]

oh sorry, forget, and this

MyOtherClass::MyOtherClass(std::string name)
{
  user_name=name;
  srand(time(NULL));
  user_id=rand()%1000000+1;
}

[ne555]

4) The destructor, copy constructor and assignment operator are not properly implemented. (only if you do need to implement them)

[smartalgorithm]

Ok...
push_back() function crash when program read vector from file... if program call push_back() function without loading vector from file all works perfectly...

[smartalgorithm]

so if vector is empty, i can add as much elements as i want to the vector by calling same push_back() function, but if in the vector there are some elements already loaded from file, calling same push_back() function making it crash....
very strange, isn't it?

[Disch]

How are you reading from the file?

Please tell me you're not doing something like this...

vector<foo> myvec;
myfile.read( (char*)&myvec, sizeof(myvec) );

Because that will not work. (This falls under #3, bad/corrupt vector)

[smartalgorithm]

here it is:

void User_ROOT::read_data(std::vector<User_Ordinary> &k)
{
  std::ifstream file_reader_1("bb_database.dat");
  int size1;

  if(!file_reader_1.is_open())
    {
      std::cout<<"Database file could not be opened. Maybe it doesn't exist !\n";
    }
  else
    {
      file_reader_1.read((char *)&size1, sizeof(size1));
      k.resize(size1, User_Ordinary("username", 1000, 0));
      file_reader_1.read((char *)&k[0], size1*sizeof(User_Ordinary));
      file_reader_1.close();
      std::cout<<"Data read successfully !!!\n";
    }
}

[Disch]

does User_Ordinary contain any complex types (like string)?

If yes, that's your problem.

[smartalgorithm]

sure....
User_Ordinary("username", 1000, 0)

"username" is string !

User_Ordinary::User_Ordinary(std::string name, int password, int money):User_empty(name)
{
  // TODO Auto-generated constructor stub
  user_password=password;
  user_money=money;
  user_cash=0;
  std::cout<<"hey\n";
}

and

User_empty::User_empty(std::string name)
{
  user_name=name;
  srand(time(NULL));
  user_id=rand()%1000000+1;
}

[smartalgorithm]

Soooo....???!!!
what i should to do?
change string to char array?

i noticed many problems with STL vectors,,,, and this one.... hahahha
give me an advice, please, im novice programmer, and disappointed by this

[smartalgorithm]

ok,
replaced std::string user_name; with char user_name[30];
all works now.
thank you very much Disch !!! :-)

but nevertheless ... STL sucks,,,, :(

[firedraco]

You'll need to write an actual operator >> for your class that loads the class. It basically boils down to you are trying to save pointers without saving what you are pointing to.

[Peter87]

Yeah, the problem is not with std::vector but in how you use it.