nullptr编译错误

#include < iostream >
#include < iomanip >
using std::cin;
using std::cout;
using std::endl;
using std::setw;

int main()
{
long* pprime(nullptr);
long trial(5); // Candidate prime
int count(3); // Count of primes found
int found(0); // Indicates when a prime is found
int max(0); // Number of primes required
cout << endl
<< "Enter the number of primes you would like (at least 4): ";
cin >> max; // Number of primes required
if(max < 4) // Test the user input, if less than 4
max = 4; // ensure it is at least 4
pprime = new long[max];
*pprime = 2; // Insert three
*(pprime + 1) = 3; // seed primes
*(pprime + 2) = 5;
do
{
trial += 2; // Next value for checking
found = 0; // Set found indicator
for(int i = 0; i < count; i++) // Division by existing primes
{
found =(trial % *(pprime + i)) == 0;// True for exact division
if(found) // If division is exact
break; // it's not a prime
}
if (found == 0) // We got one...
*(pprime + count++) = trial; // ...so save it in primes array
} while(count < max);
// Output primes 5 to a line
for(int i = 0; i < max; i++)
{
if(i % 5 == 0) // New line on 1st, and every 5th line
cout << endl;
cout << setw(10) << *(pprime + i);
}
delete [] pprime; // Free up memory
pprime = nullptr; // and reset the pointer
cout << endl;
return 0;
}