C++ std::vector iterators error - c++

Question

First of all I'm sorry for my bad english, hope you guys will understand me :) Im writing WinAPI game and my classes behave very strange: all operations with vector
crash my program so Windows says that my .exe stopped working. But when I debug these lines
I get exceptions.
This is how my class header looks like:
#ifndef FIGURE_H_INCLUDED
#define FIGURE_H_INCLUDED
#include <vector>
#include <Windows.h>
#include "Other.h"
using namespace std;
enum Figure_Type { I, J, L, O, S, T, Z };
class Figure
{
public:
/* CONSTRUCTORS */
Figure();
Figure(Figure_Type);
/* MOVEMENT */
bool Move(vector<Cell>&, Direction&);
void Drop(vector<Cell>&);
bool Rotate(vector<Cell>&);
/* OTHER */
void Draw(HDC&);
private:
/* METHODS */
void Generate();
void GenerateMasks();
void GenerateFigure();
Figure GetFigureCopy() const;
/* DATA */
Shift shift;
char mask[4][4];
vector<Cell> vCells;
Figure_Type type;
int rotation;
};
#endif
My constructors are using Generate() method, which code is:
void Figure::GenerateFigure()
{
vCells.clear();
int defPosX = 4,
defPosY = 20;
Cell cell;
for(int y = 0; y < 4; y++)
{
for(int x = 0; x < 4; x++)
{
if(mask[y][x] == '0')
{
cell.x = defPosX + x + shift.dx;
cell.y = defPosY - y + shift.dy;
vCells.push_back(cell);
}
}
}
}
And I'm getting exceptions on vCells.clear() method and (if I comment first line) vCells.push_back(cell) line. Actually every operation with vector / vector iterators crash my program even incrementing iterator, those are just the first so my code isn't running any longer after them.
Exception text:
"Unhandled exception at 0x5A4ACCD2 (msvcp110d.dll) in Tetris_completely_new.exe: 0xC000041D: An unhandled exception was encountered during a user callback."
And these exceptions are thrown on 217's line of "xutility". I commented it:
....
// MEMBER FUNCTIONS FOR _Container_base12
inline void _Container_base12::_Orphan_all()
{ // orphan all iterators
#if _ITERATOR_DEBUG_LEVEL == 2
if (_Myproxy != 0)
{ // proxy allocated, drain it
_Lockit _Lock(_LOCK_DEBUG);
for (_Iterator_base12 **_Pnext = &_Myproxy->_Myfirstiter;
*_Pnext != 0; *_Pnext = (*_Pnext)->_Mynextiter)
**(*_Pnext)->_Myproxy = 0;** // <------------ THIS LINE
_Myproxy->_Myfirstiter = 0;
}
#endif /* _ITERATOR_DEBUG_LEVEL == 2 */
}
....
Here is how my Cell struct looks like:
struct Cell
{
Cell() : x(1), y(1) { }
Cell(int _x, int _y): x(_x), y(_y) { }
void Draw(HDC&) const;
bool operator ==(const Cell& a) const { return (x == a.x && y == a.y); }
bool operator !=(const Cell& a) const { return !(*this == a); }
int x;
int y;
};
And Figure constructor:
Figure::Figure()
{
srand(time(NULL));
vCells.clear();
type = Figure_Type(rand() % 7);
rotation = 0;
shift.dx = 0;
shift.dy = 0;
Generate();
}

Answer 1

You're likely invoking undefined behaviour.
Without any more information, I'd say you're calling instance methods through stale object references/pointers (a reference taken at the time of callback registration is no longer valid?).
Also, as currently written in the question, you're generating a figure based on unitialized bytes in mask, so you'd likely want to initialize these too.
Here's a take on oa slightly modernized/cleaned up version. Note
the use of initializer lists
uniform initialization
reordered member initialization
not using using namespace in headers
moved srand into main instead of the constructor
See it Live on Coliru
#ifndef FIGURE_H_INCLUDED
#define FIGURE_H_INCLUDED
#include <vector>
#ifdef _WIN32
# include <Windows.h>
# include "Other.h"
#else
# include <cstdint>
# include <cstdlib>
# include <ctime>
using HDC = uint32_t;
#endif
struct Cell
{
Cell(int _x=1, int _y=1): x(_x), y(_y) { }
void Draw(HDC&) const;
bool operator ==(const Cell& a) const { return (x == a.x && y == a.y); }
bool operator !=(const Cell& a) const { return !(*this == a); }
int x;
int y;
};
struct Shift
{
Shift(int dx=0, int dy=0) : dx(dx), dy(dy) {}
int dx, dy;
};
enum class Direction
{
up, down, left, right
};
enum Figure_Type { I, J, L, O, S, T, Z };
class Figure
{
public:
/* CONSTRUCTORS */
Figure();
Figure(Figure_Type);
/* MOVEMENT */
bool Move(std::vector<Cell>&, Direction&);
void Drop(std::vector<Cell>&);
bool Rotate(std::vector<Cell>&);
/* OTHER */
void Draw(HDC&);
private:
/* METHODS */
void Generate();
void GenerateMasks();
void GenerateFigure();
Figure GetFigureCopy() const;
/* DATA */
char mask[4][4];
std::vector<Cell> vCells;
Figure_Type type;
int rotation;
Shift shift;
};
#endif
/*
* And I'm getting exceptions on vCells.clear() method and (if I comment first
* line) vCells.push_back(cell) line. Actually every operation with vector /
* vector iterators crash my program even incrementing iterator, those are just
* the first so my code isn't running any longer after them.
*
* Exception text:
* **"Unhandled exception at 0x5A4ACCD2 (msvcp110d.dll) in
* Tetris_completely_new.exe: 0xC000041D: An unhandled exception was
* encountered during a user callback."**
*
* And these exceptions are thrown on 217's line of "xutility". I commented it:
*
* ....
* // MEMBER FUNCTIONS FOR _Container_base12
* inline void _Container_base12::_Orphan_all()
* { // orphan all iterators
* #if _ITERATOR_DEBUG_LEVEL == 2
* if (_Myproxy != 0)
* { // proxy allocated, drain it
* _Lockit _Lock(_LOCK_DEBUG);
*
* for (_Iterator_base12 **_Pnext = &_Myproxy->_Myfirstiter;
* *_Pnext != 0; *_Pnext = (*_Pnext)->_Mynextiter)
* **(*_Pnext)->_Myproxy = 0;** // <------------ THIS LINE
* _Myproxy->_Myfirstiter = 0;
* }
* #endif // _ITERATOR_DEBUG_LEVEL == 2
* }
* ....
*
* Here is how my **Cell struct** looks like:
*/
//And **Figure constructor**:
Figure::Figure()
: mask {{0}},
vCells(),
type((Figure_Type) (rand() % 7)),
rotation(0),
shift({0,0})
{
Generate();
}
//My constructors are using Generate() method, which code is:
void Figure::Generate()
{
GenerateFigure();
}
void Figure::GenerateFigure()
{
vCells.clear();
for(int y = 0; y < 4; y++) {
for(int x = 0; x < 4; x++) {
if(mask[y][x] == '0')
vCells.push_back({4 + x + shift.dx, 20 - y + shift.dy});
}
}
}
int main()
{
srand(time(0));
Figure fig1;
Figure fig2;
}