Question

I have a function with the following declaration:

void playCard(string card);

and the following implementation:

void Player::playCard(string card)
{
    cout << "Playing " << card << "!" << endl;

    // Find iterator representing the card to be played
    vector<Card*>::iterator iter;
    for(iter = hand.begin(); iter != hand.end(); iter++)
    {
        if( (*iter)->getName() == card)
            continue;
    }

    // ERROR - Card not found in hand
    if(iter == hand.end())
        assert(false);

    // more stuff
}

The function is called from the following block of code:

// Divide string into 2 words
istringstream iss(in, istringstream::in);
string command, target;
iss >> command >> target;

if(command == "play")
{
    players.at(currentTurn)->playCard(target);
}

players is declared as:

vector<Player*> players;

The problem I’m having is that no matter what the “card” string is, I hit the card not found assertion. According to gdb:

Breakpoint 1, Player::playCard (this=0xb3a010, card=0x28ca00) at Player.cpp:138
138         cout << "Playing " << card << "!" << endl;
(gdb) print card
$1 = (string *) 0x28ca00

So within the playCard() function, the card variable is a pointer for some reason. Interestingly enough, the cout statement still displays the contents of the string correctly. Right before calling playCard(), the variable is NOT a pointer according to gdb, just an ordinary string.

Also, this is interesting:

(gdb) print iter
$1 = {_M_current = 0xb9a328}
(gdb) print iter->getName()
Couldn't find method __normal_iterator<Card**,std::vector<Card*, std::allocator<Card*> > >::getName
(gdb) print *iter
$2 = (class Card *&) @0xb9a328: 0xb9a160
(gdb) print *iter->getName()
Couldn't find method __normal_iterator<Card**,std::vector<Card*, std::allocator<Card*> > >::getName
(gdb) print (*iter)->getName()

Program received signal SIGSEGV, Segmentation fault.
0x61111178 in memcpy () from /usr/bin/cygwin1.dll

So gdb causes a segfault when I try to print out that last one, but the same code executes without any segfaults.

I have a feeling I’m dealing with some weird memory issues related to having a vector full of pointers to objects, but I can’t quite put my finger on it.

What’s going on here?

Answer 1

You want break instead of continue inside the loop.

They’re kind of similar; continue means continue with the next iteration of the loop, break means break out of the loop.