Access violation writing location 0x00000000. problems with pointers - c++

Question

I'm having trouble with some code for an assignment. The program is based on an online contest problem archive for college students.
Here is the header file:
#include <iostream>
#include <cmath>
using namespace std;
class Vito
{
public:
Vito(int relative_count); //constructor
~Vito(); //destructor
int min(); //finds minimum "distance" between vito's relatives
private:
int *streets; //pointer to array of street numbers
int sum(int index); //generates sum of distances for each of vito's relatives
void getStreetNums(); //retrieves street numbers from user
int relatives; //used globaly to set number of repititions
};
Vito::Vito(int relative_count = 0)
{
int *streets = new int[relative_count]; //allocates memory for array streets
relatives = relative_count;
getStreetNums();
}
Vito::~Vito()
{ delete [] streets; } //releases memory used by class
void Vito::getStreetNums()
{
cout << "Enter all street numbers, seperated by a space: ";
int street_num;
for (int i = 0; i < relatives; i++)
{
cin >> street_num;
streets[i] = street_num;
}
}
int Vito::min()
{
int MIN = 65546, test_distance; //initialized to maximum possible value for an integer in C++
for (int i = 0; i < relatives; i++)
{
test_distance = sum(i);
if( MIN > test_distance )
{ MIN = test_distance; }
}
return MIN;
}
int Vito::sum(int index)
{
int SUM = 0, street_num;
street_num = *(streets+index); //set value for determining distances between one house and the others
for (int i = 0; i < relatives; i++)
{ SUM += abs( street_num - streets[i] ); }
return SUM;
}
Here is the main:
#include <iostream>
#include "proj_02.h"
using namespace std;
int main()
{
int relatives, tests;
cout << "This program will supply a minimum distance between homes based on a given number of relatives and street numbers their homes are on. All entered values must be integers." << endl << endl;
cout << "Enter how many tests will be run: ";
cin >> tests;
for (int i = 0; i < tests; i++)
{
cout << "Enter how many relatives will be used in test " << i+1 << ": ";
cin >> relatives;
Vito family(relatives);
cout << "For this case, the minimum distance between each relatives house compared to each other is: " << family.min() << endl << endl;
}
}
After execution I get an error message saying "0xC0000005: Access violation writing location 0x00000000." here:
void Vito::getStreetNums()
{
cout << "Enter all street numbers, seperated by a space: ";
int street_num;
for (int i = 0; i < relatives; i++)
{
cin >> street_num;
streets[i] = street_num;
}
}
debugging shows that there is a null memory address set for streets, but I allocated memory for it earlier in the constructor. Can anyone explain what's going on here?

Answer 1

Vito::Vito(int relative_count = 0)
{
int *streets = new int[relative_count]; //allocates memory for array streets
In the constructor, you defined a local variable streets, and allocate memory for it. The local variable streets shadows the class member streets. Change it to:
Vito::Vito(int relative_count = 0)
{
streets = new int[relative_count]; //allocates memory for array streets