If statement not catching nullptr

I have a program that is supposed to take an unknown number of strings from a user. It supposed to check and see if a string has already been entered so that there will be no duplicates in the dynamic array.

The problem is that I can't get the program to recognize when an array slot has nothing in it. I've used both NULL and nullptr and neither works. What's more is even though I haven't fully initialized the array, there's still something in the location.

#include "string.h"
#include "stdio.h"
#include "stdlib.h"
#include "new"

int _tmain(int argc, _TCHAR* argv[])
{
    //Variables
    int i=0,end=0,requiresSize=1;
    char ** temp;
    char  item[256]="a";
    char ** requires;

    //Requires is initialized as an array, but the individiual slots are not
    requires = new char * [requiresSize];


    while(strcmp(item,"q-")){
        end=0;
        printf("Enter h- for help.\nEnter q- to quit.\n");
        printf("Please enter a string\n");
        gets_s(item);
        printf("%s\n",item);
        if(!strcmp(item,"h-")){
            printf("Enter a string to add to the list.\nEnter p- to print the list.\n");
            end=1;
        }   
        if(!strcmp(item,"q-")){
            break;
        }
        if(!strcmp(item,"p-")){
            if(requires[0]!=nullptr){
                for(int j=0;j<requiresSize;j++){
                    printf("%d. %s\n",j,&requires[j]);
                }
            }
            end=1;
        }
        while(end==0){
            //if search index is larger than size of the array,reallocate the array
            if(i>= requiresSize){
                temp = new char * [requiresSize*2];
                //Initialize each element in temp
                for(int j=0;j<requiresSize*2;j++){
                    temp[j]= new char[256];
                }
                for(int j =0;j<requiresSize;j++){
                    //for each element in requires, copy that element to temp
                    strncpy_s(temp[j],_TRUNCATE,requires[j],_TRUNCATE);
                }
                delete *requires;
                requires = temp;
                requiresSize = requiresSize *2;         
            }
            //if the index at requires is not empty, check to see if it is the same as given item
            if(requires[i]!= nullptr){//This should be returning false and preventing the nested if from running, but doesn't
                if(!strcmp( item,  requires[i])){//runtime error occurs here from trying to access requires[i]
                    //if they are the same, break out of the loop, item is already included
                    break;
                }else{
                    //otherwise, increase the index and check again (continue loop)
                    i++;
                    break;
                }
            }else{
                //if the index is empty, add the item to the list and break out of loop
                requires[i]= new char [256];
                strncpy_s(requires[i],_TRUNCATE,item,_TRUNCATE);
                break;
            }

        }
    }
    delete *temp;
    delete requires;
    return 0;
}

I can't figure out what I'm missing or put in the wrong place