由于未知原因，在void函数中创建（大）对象失败

Question

I have been puzzled by my program's behavior with certain object allocations for a little while now.

My main() function runs like so:

const int numOpts = 3;
string opts[numOpts] = { "Play", "Settings", "Quit" };
                        // 0       1           2
for (;;)
{
    int choice = input(numOpts); // returns 0, 1, or 2
    if (choice == 0)
    {
        Game b; // 9
        b.start(); // 10
    }
    else if (choice == 1)
        settings(); // edits global variables
    else
        break;
}

However, when I try to put lines 9 and 10 ( Game b; b.start(); ) in their own void function,

static void startGame();

int main()
{
    ...
    if (choice == 0)
        startGame();
    ...
}

static void startGame()
{
    Game b;
    b.start();
}

the program soon crashes (segmentation fault) after one iteration of the for (;;) loop. In Xcode, main() seems to forget all of its variables after the call to startGame() . Similarly,

static void startGame()
{
    Game* b = new Game;
    b->start();
    delete b;
}

also fails: however not on my own OS (OS X), but on a Linux machine. The output for this is failure looks like this: *** glibc detected *** ./Game: free(): invalid next size (fast): 0x0000000001b41d60 *** ... .

Are these problems related? I suspect that stack data for main() is somehow being freed, but if so, why does the first implementation work, but not the next two?

Answer 1

Looks like your Game class writes to memory that is outside of its control, thus corrupting the heap or stack, depending on where you allocate it. Look for buffer overruns in "Game".