[ https://issues.apache.org/jira/browse/STDCXX-492?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Martin Sebor updated STDCXX-492: -------------------------------- Severity: Inefficiency > std::string::operator+=() slow > ------------------------------ > > Key: STDCXX-492 > URL: https://issues.apache.org/jira/browse/STDCXX-492 > Project: C++ Standard Library > Issue Type: Bug > Components: 21. Strings > Affects Versions: 4.1.3 > Environment: gcc 4.1.2 on Linux/x86_64 > Reporter: Mark Brown > Assignee: Travis Vitek > Fix For: 4.2 > > Attachments: 21.string.append.perf.cpp, string.patch > > > Comparing overloads of string::operator+=() in stdcxx with the same functions > in gcc 4.1.2, stdcxx is up to twice slower than gcc: > $ time ./op_plus_equal-stdcxx 100000000 0 > real 0m2.241s > user 0m1.932s > sys 0m0.204s > $ time ./op_plus_equal-stdcxx 100000000 1 > real 0m2.540s > user 0m2.344s > sys 0m0.196s > $ time ./op_plus_equal-stdcxx 100000000 2 > real 0m1.492s > user 0m1.308s > sys 0m0.184s > $ time ./op_plus_equal-gcc 100000000 0 > real 0m0.883s > user 0m0.728s > sys 0m0.156s > $ time ./op_plus_equal-gcc 100000000 1 > real 0m1.589s > user 0m1.424s > sys 0m0.168s > $ time ./op_plus_equal-gcc 100000000 2 > real 0m1.131s > user 0m0.976s > sys 0m0.156s > #include <cassert> > #include <cstdlib> > #include <string> > int main (int argc, char *argv[]) > { > const int N = argc < 2 ? 1 : std::atoi (argv [1]); > const int op = argc < 3 ? 0 : std::atoi (argv [2]); > std::string str; > const std::string x ("x"); > if (op == 0) { > for (int i = 0; i < N; ++i) > str += 'x'; > } else if (op == 1) { > for (int i = 0; i < N; ++i) > str += "x"; > } else { > for (int i = 0; i < N; ++i) > str += x; > } > assert (str.size () == std::size_t (N)); > } -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.