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Clash Royale CLAN TAG

C++: Weird segmentation fault related to const pointers to objects

class A {
public:
A();
~A();

int** var;
void resetVar(); //sets variable to an init value
};


class B {
public:
B();
~B();

//either one of the below is declared, but not both in my code
A* const a_obj1; // const ptr to an instance of A, (option 1)
A* a_obj2; // ptr to an instance of A, (option 2)
};

A::A() {
var = new int*[2];
for( int i = 0; i < 2; i++ ) {
var[i] = new int[2];
}
resetVar();
}

A::~A() {
for ( int i = 0; i < 2; i++ ) {
delete var[i];
}
delete var;
}

A::resetVar() {
for ( int i = 0; i < 2; i++ ) {
for ( int j = 0; j < 2; j++ ) {
var[i][j] = 0; //point of segmentation fault, explained below
}
}
}

B::B():
a_obj1( new A() ) // option 1
{

a_obj2 = new A(); //option 2

a_obj2->resetVar(); //ok with option 2
a_obj1->resetVar(); //segmentation fault in this function call
}

B::~B() {
delete a_obj1;
delete a_obj2;
}


Note that this is a toned down version of my code.

There are 2 options in the above code:

B::a_obj1 is a const pointer to an instance of A

B::a_obj1

B::a_obj2 is a non-const pointer to an instance of A

B::a_obj2

A::resetVar() is called twice for each object - once in A's constructor and again in B's constructor body. The problem is only with option 1 (const pointer) and segmentation fault occurs only when A::resetVar() is called for the second time in B's constructor. I added an assertion in A::resetVar() to see if the memory for A::var actually exists. It gets triggered during the second call to resetVar() in option 1.

A::resetVar()

A::resetVar()

A::resetVar()

A::var

resetVar()

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