Simple reference variable assignment causing segfault in global pointer to object? - c++

Question

I'm getting a segfault on line 15 of my .cpp file. I'm not sure why. Various code snippets:
explosionhandler.h:
class explosionhandler {
public:
struct explosion {
...
};
vector<struct explosion> explosions;
struct explosion_type {
...
};
vector<struct explosion_type> type;
int num_types;
explosionhandler();
~explosionhandler();
void registerexplosion(int& ttype,ALLEGRO_BITMAP*& b,int seq, float a, float m,float e);
void createexplosion(int ttype,float x,float y);
void drawexplosions(ALLEGRO_BITMAP* screen);
void gettype(explosion_type& a,ALLEGRO_BITMAP*& b,int& nseq, float& aa, float& ee, float& mm);
};#endif
explosionhandler.cpp:
explosionhandler::explosionhandler()
{
num_types=0;
}
void explosionhandler::registerexplosion(int& ttype,ALLEGRO_BITMAP*& b,int seq, float a, float m,float e)
{
explosion_type n;
....
ttype = num_types; /*********** right here *******************/
num_types++;
type.push_back(n);
}
explosionhandler passed as pointer to object rocket:
rocket.h:
...
class explosionhandler;
class rocket {
public:
...
void setrocket(ALLEGRO_BITMAP*& a,ALLEGRO_BITMAP*& b, explosionhandler*& h);
...
int exptype;
...
}; #endif
rocket.cpp:
rocket::rocket()
{
...
exptype=-1;
}
void rocket::setrocket(ALLEGRO_BITMAP*& a,ALLEGRO_BITMAP*& b, explosionhandler*& h)
{
handler = h;
area.sethitboundaries(a);
fprintf(stdout,"setrocket, # of rockets in vector: %i\n",(int)rockets.size());
h->registerexplosion(exptype,b,3,(float)al_get_bitmap_width(b),(float)0,(float)-18); //called function
}
and finally main.cpp (abbreviated):
#include "rocket.h"
#include "explosionhandler.h"
#include <allegro5/allegro.h>
#include <allegro5/allegro_image.h>
#include <stdio.h>
#include <cstdlib>
#define PI 3.14159265
...
rocket rock(bullet_speed+2,width,height);
explosionhandler *handler;
...
int setup()
{
...
rock.setrocket(rk,exp,handler);
rock.setlimit(5);
al_set_target_bitmap(al_get_backbuffer(display));
...
}
...
Ok Yeah its clear now the problem was handler was not initialized. whoops.
and of course explosionhandler is a pointer in main.cpp, rocket is an object declared in main.cpp, both are globals.
Bless my little noob heart I know not what I do.

Answer 1

My psychic sense tells me that you're calling rocket::setrocket with a NULL pointer as the parameter h (or more specifically, a reference to a NULL pointer), and then you're calling h->registerexplosion() on the NULL pointer.
Don't do that. Pass in a valid pointer instead, or allocate a new object (making sure you delete it properly later).