Access reading violation when trying to use existing struct array - c++

Question

I am writing a program for my class. My program is supposed to create a passenger list. obviously, the list has to be created first, and that option in my program works fine. However when trying to access the second function(pressing B) gives me the following error in the debugger:
Exception thrown at 0x00CD4A76 in ConsoleApplication13.exe: 0xC0000005: Access violation reading location 0x00000000.
I guess that means I am trying to read into an unallocated area in the memory, therefore, the struct array I am using was not created. I am confused since the first option does work, and I am passing the same pointer to both functions therefore the pointer points to the array created in function A.
#include <iostream>
#include <string>
#define _CRT_SECURE_NO_WARNINGS
using namespace std;
struct date
{
int year;
int day;
int month;
};
struct seat
{
int row;
char place;
};
struct pass
{
char * passname;
date bookdate;
seat location;
};
int lastindex;
int initList(pass *p, int x);
int addPass(pass *p, date *D, pass *newpass, int length);
void main()
{
pass *p = {};
int length = 0;
char choice;
do {
cout << "Welcome to FlightDesigner2017.\nEnter one of the following keys to continue:\nA: Create a list of passengers.\nB: Add a passenger to the flight.\n";
cin >> choice;
switch (choice)
{
case 'A':
{
int x;
cout << "How many passengers are on your flight? \n";
cin >> x;
length = initList(p, x);
break;
}
case 'B':
{
pass *newpass=0;
date *D = 0;
switch (addPass(p, D, newpass, length))
{
case '1':
cout << "Passenger successfully added."; break;
case '-3':
cout << "No seats available."; break;
case '-1':
cout << "Seat taken. Try again."; break;
case '-2':
cout << "Passenger is already on the flight."; break;
}
break;
}
}
}
while (choice=!0);
}
int addPass(pass *p, date *D, pass *newpass, int length)
{
#define TAKEN -1
#define SAMENAME -2
#define NOSEATS -3
#define SUCCESS 1
for (int init = 0; init < length; init++)
{
int counter=0;
for (int j = 0; j < length; j++) //empty seats check
{
if (strcmp(p[j].passname , NULL)!=0)
counter++;
}
if (counter == length)
return NOSEATS;
cout << "Enter a seat and row (seat A to F, row 1 to 50): \n"; //taken check
cin >> newpass->location.place >> newpass->location.row;
cout << "\nWhat is the flight date (DD/MM/YYYY)? \n";
cin >> D->day >> D->month >> D->year;
for (int k = 0; k < length; k++)
{
if (D->day == p[k].bookdate.day && D->month == p[k].bookdate.month && D->year == p[k].bookdate.year
&& p[k].location.place == newpass->location.place && p[k].location.row == newpass->location.row)
return TAKEN;
}
cout << "What is the passenger name? \n"; // name check
cin >> newpass->passname;
for (int i = 0; i < length; i++)
{
if (strcmp(newpass->passname,p[i].passname)==0)
return SAMENAME;
}
strcpy(newpass->passname, p[init].passname);
p[init].location.place = newpass->location.place;
p[init].location.row = newpass->location.row;
p[init].bookdate.year = D->year;
p[init].bookdate.month = D->month;
p[init].bookdate.day = D->day;
char ans;
cout << "Enter another passenger? (Y/N)\n";
cin >> ans;
if (ans == 'N')
return SUCCESS;
}
return SUCCESS;
}
int initList(pass *p, int length)
{
p = new pass[length];
for (int i = 0; i < length; i++)
p[i].passname = NULL;
return length;
}
Any explanation on how can I fix this error will help. thanks in advance.