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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
//[n1962_sqrt
#include <boost/contract.hpp>
#include <cmath>
#include <cassert>
long lsqrt(long x) {
long result;
boost::contract::check c = boost::contract::function()
.precondition([&] {
BOOST_CONTRACT_ASSERT(x >= 0);
})
.postcondition([&] {
BOOST_CONTRACT_ASSERT(result * result <= x);
BOOST_CONTRACT_ASSERT((result + 1) * (result + 1) > x);
})
;
return result = long(std::sqrt(double(x)));
}
int main() {
assert(lsqrt(4) == 2);
return 0;
}
//]
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