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POstd::transform how to not return (and not throw), just skip?
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  1. POstd::transform how to not return (and not throw), just skip?
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    copied!<p>I want to display folder contents displaying (not having any folder system) So Having a <code>std::set&lt;string_file_names&gt;</code> with <code>std::strings</code> in it and some given path to some dir we want to search for folder contents as in normal fs. so having set of:</p> <pre><code> set&lt;string&gt; demo_set; demo_set.insert("file1"); demo_set.insert("file2"); demo_set.insert("folder/file1"); demo_set.insert("folder/file2"); demo_set.insert("folder/folder/file1"); demo_set.insert("folder/folder/file2"); demo_set.insert("bin/obj/Debug/CloudServerPrototype/ra.write.1.tlog"); demo_set.insert("bin/obj/Debug/CloudServerPrototype/rc.write.1.tlog"); demo_set.insert("bin/obj/Debug/vc100.idb"); demo_set.insert("bin/obj/Debug/vc100.pdb"); </code></pre> <p>and search string <code>"bin/obj/Debug/"</code> we want to get 3 Items - folder, 2 files:</p> <pre><code>CloudServerPrototype/ vc100.idb vc100.pdb </code></pre> <p>But we get also an empty line. How to not get it and how to throw an error in case of non items found?</p> <p>Entire code:</p> <pre><code>#include &lt;iostream&gt; #include &lt;algorithm&gt; #include &lt;set&gt; #include &lt;string&gt; #include &lt;iterator&gt; using namespace std; struct get_pertinent_part { const std::string given_string; get_pertinent_part(const std::string&amp; s) :given_string(s) { } std::string operator()(const std::string&amp; s) { std::string::size_type first = 0; if (s.find(given_string) == 0) { first = given_string.length(); } else { return ""; } std::string::size_type count = std::string::npos; std::string::size_type pos = s.find_last_of("/"); if (pos != std::string::npos &amp;&amp; pos &gt; first) { count = pos + 1 - first; } return s.substr(first, count); } }; void directory_listning_without_directories_demo() { set&lt;string&gt; output; set&lt;string&gt; demo_set; demo_set.insert("file1"); demo_set.insert("file2"); demo_set.insert("folder/file1"); demo_set.insert("folder/file2"); demo_set.insert("folder/folder/file1"); demo_set.insert("folder/folder/file2"); demo_set.insert("bin/obj/Debug/CloudServerPrototype/ra.write.1.tlog"); demo_set.insert("bin/obj/Debug/CloudServerPrototype/rc.write.1.tlog"); demo_set.insert("bin/obj/Debug/vc100.idb"); demo_set.insert("bin/obj/Debug/vc100.pdb"); std::transform(demo_set.begin(), demo_set.end(), std::inserter(output, output.end()), get_pertinent_part("bin/obj/Debug/")); std::copy(output.begin(), output.end(), std::ostream_iterator&lt;std::string&gt;(std::cout, "\n")); } int main() { directory_listning_without_directories_demo(); cin.get(); return 0; } </code></pre> <p>code sample based on <a href="https://stackoverflow.com/questions/7169320/setstring-how-to-list-not-strings-starting-with-given-string-and-ending-with/7169544#7169544">this</a> grate answer.</p>
 

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