33 lines
825 B
C++
33 lines
825 B
C++
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// Copyright (C) 2008-2018 Lorenzo Caminiti
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// Distributed under the Boost Software License, Version 1.0 (see accompanying
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// file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
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// See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
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//[n1962_sqrt
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#include <boost/contract.hpp>
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#include <cmath>
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#include <cassert>
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long lsqrt(long x) {
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long result;
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boost::contract::check c = boost::contract::function()
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.precondition([&] {
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BOOST_CONTRACT_ASSERT(x >= 0);
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})
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.postcondition([&] {
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BOOST_CONTRACT_ASSERT(result * result <= x);
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BOOST_CONTRACT_ASSERT((result + 1) * (result + 1) > x);
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})
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;
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return result = long(std::sqrt(double(x)));
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}
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int main() {
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assert(lsqrt(4) == 2);
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return 0;
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}
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//]
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