Resource ownership with RAII

The idea

Start with references, scopes, and object lifetimes. Resource management becomes easier when an object owns a resource and its destructor releases it. This pattern is called RAII. Standard containers already apply it to their storage. For a separately allocated object with one owner, unique_ptr expresses exclusive ownership and performs cleanup when the owner is destroyed, including during normal exception unwinding.

A unique_ptr cannot be copied into a second independent owner. Moving transfers its ownership; after a successful move the source unique_ptr is empty. std::move itself is a cast that permits move-aware operations, not a universal promise that every object becomes empty. Here the receiving unique_ptr performs the actual transfer. Prefer make_unique to a raw allocation, and borrow through references when ownership should stay with the caller.

#include <iostream>
#include <memory>
#include <utility>
int main(){auto first=std::make_unique<int>(12); auto second=std::move(first);
 std::cout<<static_cast<bool>(first)<<" "<<*second<<"\n";}

0 12

The second unique_ptr owns the integer. The first is empty and can be tested, but must not be dereferenced.