c++ - program terminates unexpectedly after the introduction of catch block -

i have piece of code runs normally, breaks when add exception handling. beginner , here's code

this code works (for brevity's sake include guards not shown):

in plane.h:

#include "vector.h" //which, point.h, inherits orderedpair.h class plane {     public:         plane(const std::string &label);         plane(const plane &);         virtual ~plane();          void insert(const orderedpair &);         void label(const std::string & label);         std::string label() const {return _label;}      protected:         std::string _label;         bool operator==(const plane &rhs) const {return label() == rhs.label();}         bool operator<(const plane & rhs) const {return label() < rhs.label();} }; 

in plane.cpp

#include <set> plane::plane(const std::string &label) : _label(label) {      getuniverse().insert(this); }  /*global objects*/  extern std::set<plane *>& getuniverse() {     static std::set<plane *>universe;     return universe; }  extern plane& getdefaultplane() {     static plane default("default");     return default; }  void printworld() {     (auto : getuniverse())         std::cout << (*getuniverse().find(i))->label() << std::endl; } 

and in main:

//mingw32 4.9 code::blocks 16.01 windows vista(!!) 64bit -std=c++11 #include <iostream> #include "vector.h" //includes point.h includes orderedpair.h #include "plane.h"  using namespace std;  namespace {     struct initializer {;         initializer();     }; }  int main() {  static initializer init; point a("a", 1, 1);  plane p("p"); plane duplicate("default");  printworld(); return 0; }  initializer::initializer() {    // trigger construction of default plane    getdefaultplane(); } 

then include exception in plane.h , add following @ top:

class e : public std::exception {     const char *msg = nullptr; public:     e(const char *m) throw() : msg(m) {}     const char *what() const throw() {return msg;} }; const e duplicateobj("object exists!\n"); 

it compiles , runs, without problem. change constructor of plane in way (to make sure label has not been used before):

plane::plane(const std::string &label) : _label(label) {      (auto : getuniverse()) {            if ((*getuniverse().find(i))->label() == _label) throw duplicateobj;      }     getuniverse().insert(this); } 

and comment out instantiation of duplicate plane in main (to avoid triggering throw). compiles , runs, no problem.

then wrap object instantiation lines in try/catch block in main:

try {     point a("a", 1, 1);     plane p("p");     //plane duplicate("default"); } catch (const e& e) {     cerr << e.what() << endl; } catch (const exception &e) {     cerr << e.what() << endl; } 

it compiles crashes following result:

process returned -1073741819 (0xc0000005)   execution time : 9.537 s press key continue. 

isn't problem of exceptions.

it's problem of pointer , scope.

if i'm not wrong.

your plane constructor insert (getuniverse().insert(this);) this pointer in static global set (static std::set<plane *>universe; in getuniverse()).

then, use global set in last instruction of main() (printworld()).

before introduction of try/catch blocks, scope of plane p("p"); object full main() function; pointer p valid pointer when call printworld.

but when write

try {     plane p("p");     // end of p scope  }  // p out of scope; pointer p, in universe, invalid  printworld(); // use of invalid pointer p 

the scope of p try block; so, when call printworld() out of try block, universe contain pointer destroied object.

crash!

p.s.: sorry bad english.