c++ - Segmentation Fault with a pointer to an object holding an unordered_set - 


#include <unordered_set>  class c { public:     std::unordered_set<int> us; };  int main() {     c* c;     c->us.insert(2); // segmentation fault }

what doing wrong?

you segmentation fault because pointer has not been assigned:

c* c = new c; // <<== add c->us.insert(2); delete c;    // <<== free memory

unlike objects declared objects, not pointers (e.g. c c;) pointers need initialized: should either assign them address of existing object, or allocate memory new object using operator new. dereferencing uninitialized pointers considered undefined behavior, causing segmentation faults.


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