PRIME GENERATOR PROBLEM! Kindly Help

[lalitha_sof]

#include<iostream>
#include<math.h>
using namespace std;
class primeGen{
	   long long a1,b;
	   public:
	      void getdata();
	      void prime();
	 };
 void primeGen::getdata()
 {
 cin>>a1>>b;
 }
 void primeGen::prime()
 {
	long long p,j;
	long long *a= new long long[100001];
	for(p=2;p<=b;p++)
		a[p]=1;
    double m=sqrt((long double)b);
for(p=2;p<=m;p++)
{
	if(a[p]!=0)
		j=p*p;
	while(j<=b)
		{
			a[j]=0;
			j=j+p;
		}
}
for(p=a1;p<=b;p++)
{
	if(a[p]== 1)
		{
			cout<<a[p]<<"\n";
		}
}
}
 int main()
 {
 	int i,n;
 	cin>>n;
	primeGen ob[10];
 	for(i=0;i<n;i++)
 	{
  		ob[i].getdata();
 	}
 	for(i=0;i<n;i++)
	{
 		ob[i].prime();
 		cout<<"\n";
  	}
  	return 0;
 }

I keep getting segmentation error for the above code. Kindly help me out with this code.

[leppyr64]

You are reading or writing outside of your array bounds.

PS: changing your array size to 10^9 won't help.

[lalitha_sof]

Thanks leppy !

[vanninh01]

But, when I use bool *a = new bool [1000000001]; this is SIGABRT error ( The SIGABRT signal is sent to a process to tell it to abort, i.e. to terminate. The signal is usually initiated by the process itself when it calls abort function of the C Standard Library, but it can be sent to the process from outside as well as any other signal.)