Question

help with these c++ questions I believe I had submitted the wrong answer and want to know if I had got it right

[8 points) Consider the following code: 16 Foo :: Foo() { delete () arr; 2 17 } 4 class Food public: Foo(); *Foo(); private: int #arr: }; 18 19 20 21 5 6 void init (Fool param) { Foo obj: param = obj: 22 23 8 } 24 0 Foo :: Foo() { arr = new int (3); for (int i = 0; i < 3; i++){ arri] = ; int main() { Foo myobj: 2 25 26 27 28 29 3 } init (myobj); // checkpoint a) 1 5 30 } You might notice that as the program runs after checkpoint a), the values stored in myobj.arr will start changing unpredictably. Explain with details why this is happening, and provide a solution to fix the problem(s).

Answer 1

problem:

class Foo{
public:
Foo();
~Foo();
private:
int *arr;
};
Foo::Foo(){
arr = new int[3];
for(int i=0;i<3;i++)
{
arr[i]=i;
}
}
Foo::~Foo(){
delete []arr;
}
void init(Foo& param)
{//the problem is in this method
Foo obj;//here we are creating a static local object of Foo, its life span is in this method only
param =obj;//now here we are assigning this local object to passed parameter param
//so for now,in this method param points the memory of the object obj
//but whenever this method terminates, the memory created for obj is also freed
//means after termination of this method, param points to meaning less address
//hence myobj.arr will start changing unpredictably
}
int main()
{
Foo myobj;
init(myobj);
return 0;   
}

solution:

class Foo{
public:
Foo();
~Foo();
private:
int *arr;
};
Foo::Foo(){
arr = new int[3];
for(int i=0;i<3;i++)
{
arr[i]=i;
}
}
Foo::~Foo(){
delete []arr;
}
void init(Foo& param)
{
Foo *obj = new Foo();//creating dynamic memory, it spans throughout the program
//assigning it to param
param = *obj;
  
  
}
int main()
{
Foo myobj;
init(myobj);
return 0;   
}