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- // Copyright (C) 2008-2018 Lorenzo Caminiti
- // Distributed under the Boost Software License, Version 1.0 (see accompanying
- // file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
- // See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
- #include <boost/contract.hpp>
- int gcd(int const a, int const b) {
- int result;
- boost::contract::check c = boost::contract::function()
- .precondition([&] {
- BOOST_CONTRACT_ASSERT(a > 0);
- BOOST_CONTRACT_ASSERT(b > 0);
- })
- .postcondition([&] {
- BOOST_CONTRACT_ASSERT(result <= a);
- BOOST_CONTRACT_ASSERT(result <= b);
- })
- ;
- int x = a, y = b;
- while(x != y) {
- if(x > y) x = x - y;
- else y = y - x;
- }
- return result = x;
- }
- //[check
- int main() {
- // Implementation checks (via nullary functor).
- boost::contract::check c = [] {
- BOOST_CONTRACT_ASSERT(gcd(12, 28) == 4);
- BOOST_CONTRACT_ASSERT(gcd(4, 14) == 2);
- };
- return 0;
- }
- //]
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