const string& show_string(){
    std::shared_ptr<std::string> p = std::make_shared<std::string>("test");
    return *p;
}

A novice question：Will this usage cause dangling reference？

CodePudding user response：

Yes

std::shared_ptr will delete the object it owns when the last std::shared_ptr sharing ownership of that object is destroyed. In this case, p is the only std::shared_ptr pointing to your string, and it is local to show_string, so that string will be destroyed as soon as show_string returns, leaving the returned reference dangling.