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POset_difference and set_intersection simultaneously
 

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    <p>I'm wondering if there is any facility in the standard library to simultaneously compute the set intersection and set difference between two sorted ranges. Something with a signature along the lines of:</p> <pre><code>template &lt;class Input1, class Input2, class Output1, class Output2, class Output3&gt; Output3 decompose_sets (Input1 first1, Input1 last1, Input2 first2, Input2 last2, Output1 result1, Output2 result2, Output3 result3 ); </code></pre> <p>Such that after a call to <code>decompose sets</code>, <code>result1</code> contains all the elements in <code>[first1,last1)</code> which are not in <code>[first2,last2)</code>, <code>result2</code> contains all the elements in <code>[first2,last2)</code> which are not in <code>[first1,last1)</code>, and <code>result3</code> contains all element which are common in <code>[first1,last1)</code> and <code>[first2,last2)</code>.</p> <p>The example implementations of <a href="http://www.cplusplus.com/reference/algorithm/set_difference/" rel="nofollow"><code>set_difference</code></a> and <a href="http://www.cplusplus.com/reference/algorithm/set_intersection/" rel="nofollow"><code>set_intersection</code></a> from cplusplus.com seem like they can help me to create an efficient implementation which performs only one scan instead of three. If it's in the standard library, though, I'd hate to reinvent the wheel.</p> <p>Example, by request:</p> <p>Given two sets a={0, 1, 2, 3, 4} and b={2, 4, 5, 6} then I would like to build the following three sets:</p> <ul> <li>only_a = {0,1,3}</li> <li>only_b = {5,6}</li> <li>common = {2,4}</li> </ul>
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    1. COHow come `[first1,last2)` ?
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    2. COCould you give an example of what you want to achive, for example with sets {0, 1, 2, 3} and {0, 2, 4, 6} ?
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    3. CO@P0W b/c of typos
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