c++ - Segfault when imbueing stringstream with custom locale -

based on answers here question of how format numbers comma, using following code:

#include <locale> #include <stringstream>  namespace {  class comma_numpunct : public std::numpunct<char> {   protected:     virtual char do_thousands_sep() const     {         return ',';     }      virtual std::string do_grouping() const     {         return "\03";     } };  }   /* convert number string using comma thousands separator. */ string thousands(const int x) {      /* custom locale ensure thousands separator comma */     comma_numpunct* comma_numpunct_ptr = new comma_numpunct();     std::locale comma_locale(std::locale(), comma_numpunct_ptr);      stringstream ss;     ss.imbue(comma_locale); // apply locale stringstream     ss << x;      /* garbage collection */     delete comma_numpunct_ptr;      return ss.str(); } 

gdb gives following backtrace:

program received signal sigsegv, segmentation fault. 0x0000000000000021 in ?? () (gdb) bt #0  0x0000000000000021 in ?? () #1  0x00007ffff7701535 in std::locale::_impl::~_impl() () /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #2  0x00007ffff770166d in std::locale::~locale() () /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #3  0x000000000044b93e in thousands (x=358799) @ ../globals_utilities.cpp:104 #4  0x000000000045650d in main (argc=1, argv=0x7fffffffdf58) @ ../main.cpp:67 

so, problem (i believe) attempt @ freeing new'd memory. don't know how work around this. (i can't use std::unique_ptr because i'm not compiling c++11 support.)

how can fix segfault without leaking memory?

your problem locale facet (numpunct). if pass locale via constructor , references of facet 0 locale delete facet.

you might do:

comma_numpunct(size_t refs = 0) :   numpunct(refs) {} 

and

comma_numpunct* comma_numpunct_ptr = new comma_numpunct(1); 

or better omit:

// double delete // delete comma_numpunct_ptr; 

you may omit allocation of facet:

string thousands(const int x) {    comma_numpunct numpunct(1);    std::locale comma_locale(std::locale(), &numpunct);    std::stringstream ss;    ss.imbue(comma_locale);    ss << x;    return ss.str(); } 

from 22.3.1.1.2 class locale::facet

the refs argument constructor used lifetime management.

— refs == 0, implementation performs delete static_cast(f) (where f pointer facet) when last locale object containing facet destroyed; refs == 1, implementation never destroys facet.