next_prime.pass.cpp revision 06086258d3d8c48a916ec51c33e1ad8f46821b81 
1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// REQUIRES: long_tests
11
12// Not a portable test
13
14// <__hash_table>
15
16// size_t __next_prime(size_t n);
17
18// If n == 0, return 0, else return the lowest prime greater than or equal to n
19
20#include <__hash_table>
21#include <cassert>
22
23bool
24is_prime(size_t n)
25{
26    switch (n)
27    {
28    case 0:
29    case 1:
30        return false;
31    }
32    for (size_t i = 2; i*i <= n; ++i)
33    {
34        if (n % i == 0)
35            return false;
36    }
37    return true;
38}
39
40int main()
41{
42    assert(std::__next_prime(0) == 0);
43    for (std::size_t n = 1; n <= 100000; ++n)
44    {
45        std::size_t p = std::__next_prime(n);
46        assert(p >= n);
47        for (std::size_t i = n; i < p; ++i)
48            assert(!is_prime(i));
49        assert(is_prime(p));
50    }
51}
52