cxx/test/containers/unord/next_prime.pass.cpp
2010-05-11 21:36:01 +00:00

50 lines
1.0 KiB
C++

//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Not a portable test
// <__hash_table>
// size_t __next_prime(size_t n);
// If n == 0, return 0, else return the lowest prime greater than or equal to n
#include <__hash_table>
#include <cassert>
bool
is_prime(size_t n)
{
switch (n)
{
case 0:
case 1:
return false;
}
for (size_t i = 2; i*i <= n; ++i)
{
if (n % i == 0)
return false;
}
return true;
}
int main()
{
assert(std::__next_prime(0) == 0);
for (std::size_t n = 1; n <= 100000; ++n)
{
std::size_t p = std::__next_prime(n);
assert(p >= n);
for (std::size_t i = n; i < p; ++i)
assert(!is_prime(i));
assert(is_prime(p));
}
}