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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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