SISGEV error despite allocating memory on heap? (generating primes) - c++

Question

I have written code to generate prime numbers in a range (using a modified Sieve of Eratosthenes) , as competitive programming. The code works fine on my Visual Studio, but gives a SISGEV on the website. I use this,
static bool *prime = new bool[1000000001];
to declare memory. And can not understand the reason behind the SISGEV.
Below is the function, whose parameters are the lower limit m, and the upper limit n.
Elements of index >m which are not prime are marked false.
static bool *prime = new bool[1000000009];
void SieveOfEratosthenes(int m, int n)
{
// Create a boolean array "prime[0..n]" and initialize
// all entries it as true. A value in prime[i] will
// finally be false if i is Not a prime, else true.
memset(prime, true, n + 11);
int m2;
if (m > 10) {
m2 = m / 10;
m2 = m2 * 10;
m2 = (2 * m2) / 5;
}
else
m2 = 4;
prime[1] = false;
prime[2] = true;
prime[3] = true;
prime[5] = true;
for (int i = m2; i <= n; i += 2) {
if ( (5*2)/2 >= n) break;
prime[i] = false;
prime[(3 * i) / 2] = false;
prime[(5 * i) / 2] = false;
}
int m3;
m3 = m % 7;
m3 = m - m3;
for (int p = 7; (p)*(p) <= n; p += 6) {
// If prime[p] is not changed, then it is a prime
if (prime[p] == true) {
// Update all multiples of p,
for (int i = p; i <= n; i += p) {
prime[m3+i] = false; //cout << i << " ";
if (prime[m3 + p+ 4]) prime[((p+4)*i)/p] = false;
if (prime[m3 + p + 6]) prime[((p+6)*i)/p] = false;
}
}
prime[7] = true;
prime[11] = true;
prime[13] = true;
}
// Print all prime numbers
for (int p = m; p <= n; p++)
if (prime[p])
cout << p << endl;
}
int main() {
//other code
delete[] prime;
}

Answer 1

Your pointer is a static variable. In C++ the initialization of a static variable happens only once. The delete[] statement however, is executed for every function call.
Do not tilt at windmills and use std::vector instead of rolling a raw-memory solution.
A simple implementation using std::vector: (Adding the extended functionality is left as an exercise to the reader.)
#include <vector>
#include <cmath>
#include <cstddef>
#include <algorithm>
#include <iostream>
std::vector<std::size_t> eratosthenes(std::size_t const n)
{
std::vector<bool> A(n, true);
std::vector<std::size_t> r;
auto const limit = static_cast<std::size_t>(
std::ceil(std::sqrt(static_cast<double>(n))));
// check all numbers up to sqrt(n)
for (std::size_t i = 2; i <= limit; ++i)
{
// if i is prime,
if (A[i])
{
// i is prime, put it into return vector
r.push_back(i);
// set all multiples of i (below n) to false
for (std::size_t j = i*i; j < n; j+=i)
{
A[j] = false;
}
}
}
// fill rest of the primes > sqrt(n) into r
if (!r.empty())
{
for (auto i = limit+1u; i < n; ++i)
{
if (A[i]) r.push_back(i);
}
}
return r;
}
Printing it:
int main()
{
for (auto v : eratosthenes(120))
{
std::cout << v << "\n";
}
return 0;
}