libs/contract/example/features/loop.cpp

   1
   2 // Copyright (C) 2008-2018 Lorenzo Caminiti
   3 // Distributed under the Boost Software License, Version 1.0 (see accompanying
   4 // file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
   5 // See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
   6
   7 #include <boost/contract.hpp>
   8 #include <vector>
   9 #include <algorithm>
  10 #include <limits>
  11
  12 int main() {
  13     std::vector<int> v;
  14     v.push_back(1);
  15     v.push_back(2);
  16     v.push_back(3);
  17
  18     //[loop
  19     int total = 0;
  20     // Contract for a for-loop (same for while- and all other loops).
  21     for(std::vector<int>::const_iterator i = v.begin(); i != v.end(); ++i) {
  22         boost::contract::old_ptr<int> old_total = BOOST_CONTRACT_OLDOF(total);
  23         boost::contract::check c = boost::contract::function()
  24             .precondition([&] {
  25                 BOOST_CONTRACT_ASSERT(
  26                         total < std::numeric_limits<int>::max() - *i);
  27             })
  28             .postcondition([&] {
  29                 BOOST_CONTRACT_ASSERT(total == *old_total + *i);
  30             })
  31         ;
  32
  33         total += *i; // For-loop body.
  34     }
  35     //]
  36
  37     assert(total == 6);
  38     return 0;
  39 }
  40