Visual C++ Error : Uninitialised variable

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>

void display(char *, int);

int main()
{
	char *ip;
	char *op[4];
	int j, i=0, num=0, count[4]={0, 0, 0, 0};
	
	printf("Enter the response of GSM Module : ");
	//gets(ip);
	scanf_s("%s",ip);
	printf("%s",ip);
	//printf("Hello");
	for(i;;i++)
	{
		printf("%c",*(ip+i));
		if(*(ip+i)=='"')
		{
			op[num]=ip+i+1;
			for(j=i+1;;j++)
			{
				printf("%c",*(ip+j));
				if(*(ip+j)=='"')
				{
					count[num]=j-i-2;
					num+= 1; 
					i=j;
					break;
				}
			}
		}
		if(*(ip+i)=='\n')
			break;
	}
	///printf("ip : %d Count : %d op : %d difference : %d\n",ip, count, op, (op-ip));
	printf("\nSender's Number : ");
	display(op[0],count[0]);
	printf("\nMessage Status : ");
	display(op[1],count[1]);
	printf("\n Date & Time : ");
	display(op[2],count[2]);
	printf("\nReceived Message : ");
	display(op[3],count[3]);
	_getch();
	return 0;	
}

void display(char *dip, int c)
{
	int i;
	for(i=0;i<=c;i++)
		printf("%c",*(dip+i));
}

In this code, ip is a character pointer. Generally in C variables without initialisation is normal. But here it gives the error of uninitialised variable ip used.

I have tried to initialise ip by setting it equal to NULL, but it also gives me another error.

Earlier I have successfully compiled and run a code without initialisation and by modifying that code only, I generated this code.

Please suggest me what to do, as I can't find any problem in my code.