1 files changed, 34 insertions, 0 deletions
diff --git a/src/boost/libs/contract/example/features/introduction.cpp b/src/boost/libs/contract/example/features/introduction.cpp
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+++ b/src/boost/libs/contract/example/features/introduction.cpp
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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 <limits>
+#include <cassert>
+
+//[introduction
+#include <boost/contract.hpp>
+
+void inc(int& x) {
+    boost::contract::old_ptr<int> old_x = BOOST_CONTRACT_OLDOF(x); // Old value.
+    boost::contract::check c = boost::contract::function()
+        .precondition([&] {
+            BOOST_CONTRACT_ASSERT(x < std::numeric_limits<int>::max()); // Line 17.
+        })
+        .postcondition([&] {
+            BOOST_CONTRACT_ASSERT(x == *old_x + 1); // Line 20.
+        })
+    ;
+
+    ++x; // Function body.
+}
+//]
+
+int main() {
+    int x = 10;
+    inc(x);
+    assert(x == 11);
+    return 0;
+}
+