I am not able to understand the behavior of the following program
#include <iostream>
#include<memory>
#include<string>
using namespace std;
int main() {
auto p1 = make_shared<string> (10,'S');
cout<<"p1 use_count = "<<p1.use_count()<<endl;
shared_ptr<string> p2(new string()) ;
p1 = p2;
cout<<"p2 use_count = "<<p2.use_count()<<endl;
cout<<"second p1 use_count = "<<p1.use_count()<<endl;
return 0;
}
Output
++++++++++++++++
p1 use_count = 1
p2 use_count = 2
second p1 use_count = 2
I can understand the first two print. At beginning p1 points to one
string so the reference count is 1. When the statement p1=p2;
executes p2's reference count gets incremented to 2 but at the same
time I was expecting that p1's reference count to be decremented by 1
as p1 would be pointing to p2 now. Please let me know where my
understanding is going wrong?
p1 *is* p2. There are to references (p1 and p2) to the string initially
assigned to p1. Both have to go out of scope for the string to be deleted.