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 // Not a portable test 11 12 // <__hash_table> 13 14 // size_t __next_prime(size_t n); 15 16 // If n == 0, return 0, else return the lowest prime greater than or equal to n 17 18 #include <__hash_table> 19 #include <cassert> 20 21 bool 22 is_prime(size_t n) 23 { 24 switch (n) 25 { 26 case 0: 27 case 1: 28 return false; 29 } 30 for (size_t i = 2; i*i <= n; ++i) 31 { 32 if (n % i == 0) 33 return false; 34 } 35 return true; 36 } 37 38 int main() 39 { 40 assert(std::__next_prime(0) == 0); 41 for (std::size_t n = 1; n <= 100000; ++n) 42 { 43 std::size_t p = std::__next_prime(n); 44 assert(p >= n); 45 for (std::size_t i = n; i < p; ++i) 46 assert(!is_prime(i)); 47 assert(is_prime(p)); 48 } 49 } 50
