c++ - two different behavior in using default and overridden copy constructor -

when override copy constructor why segfaults in first delete itself. output:

$./a.out inside ctor inside copy-ctor in somefunc inside dtor *** glibc detected *** ./a.out: free(): invalid pointer: 0xb75f3000 *** 

if not override copy-ctor see s1.printval() getting called , there seg fault in *ptr expected.

why there 2 different behavior , without default , overridden copy-ctor?

#include<iostream> using namespace std; class sample { public:     int *ptr;     sample(int i)     {         cout << "inside ctor" << endl;         ptr = new int(i);     }     sample(const sample &rhs)     {         cout << "inside copy-ctor" << endl;     }     ~sample()     {         cout << "inside dtor" << endl;         delete ptr;     }     void printval()     {         cout <<" inside printval()."<<endl;         cout << "the value " << *ptr<<endl;     } }; void somefunc(sample x) {     cout << "say in somefunc " << endl; }  int main() {     sample s1= 10;     somefunc(s1);     s1.printval();     return 0; } 

in copy-ctor, don't copy ptr, meaning value unspecified, , you'll deleting unspecified pointer (instead of double-deleting normal pointer defauly copy-ctor).