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82 lines
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<title>Undetected overflow</title>
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<div class="titlepage"><div><div><h3 class="title">
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<a name="safe_numerics.tutorial.2"></a>Undetected overflow</h3></div></div></div>
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<p>A variation of the above is when a value is incremented/decremented
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beyond it's domain. This is a common problem with for loops.</p>
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<pre class="programlisting">#include <cassert>
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#include <stdexcept>
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#include <iostream>
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#include "../include/safe_integer.hpp"
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//#include "../include/safe_compare.hpp"
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void detected_msg(bool detected){
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std::cout << (detected ? "error detected!" : "error NOT detected! ") << std::endl;
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}
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int main(int argc, const char * argv[]){
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std::cout << "example 2:";
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std::cout << "undetected overflow in data type" << std::endl;
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try{
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int x = INT_MAX;
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// the following silently produces an incorrect result
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++x;
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std::cout << x << " != " << INT_MAX << " + 1" << std::endl;
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detected_msg(false);
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}
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catch(...){
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assert(false); // never arrive here
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}
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// solution: replace int with safe<int>
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try{
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using namespace boost::numeric;
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safe<int> x = INT_MAX;
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// throws exception when result is past maximum possible
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++x;
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assert(false); // never arrive here
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}
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catch(std::range_error & e){
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std::cout << e.what();
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detected_msg(true);
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}
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return 0;
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}
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</pre>
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<td align="right"><div class="copyright-footer">Copyright © 2012 Robert Ramey<p><a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">Subject to Boost
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Software License</a></p>
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