{"action":"opened","issue":{"url":"https://api.github.com/repos/Mooophy/Cpp-Primer/issues/306","labels_url":"https://api.github.com/repos/Mooophy/Cpp-Primer/issues/306/labels{/name}","comments_url":"https://api.github.com/repos/Mooophy/Cpp-Primer/issues/306/comments","events_url":"https://api.github.com/repos/Mooophy/Cpp-Primer/issues/306/events","html_url":"https://github.com/Mooophy/Cpp-Primer/issues/306","id":96739656,"number":306,"title":"question on Ex12.1","user":{"login":"xiaodi528","id":9313435,"avatar_url":"https://avatars.githubusercontent.com/u/9313435?v=3","gravatar_id":"","url":"https://api.github.com/users/xiaodi528","html_url":"https://github.com/xiaodi528","followers_url":"https://api.github.com/users/xiaodi528/followers","following_url":"https://api.github.com/users/xiaodi528/following{/other_user}","gists_url":"https://api.github.com/users/xiaodi528/gists{/gist_id}","starred_url":"https://api.github.com/users/xiaodi528/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/xiaodi528/subscriptions","organizations_url":"https://api.github.com/users/xiaodi528/orgs","repos_url":"https://api.github.com/users/xiaodi528/repos","events_url":"https://api.github.com/users/xiaodi528/events{/privacy}","received_events_url":"https://api.github.com/users/xiaodi528/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-07-23T06:06:03Z","updated_at":"2015-07-23T06:06:03Z","closed_at":null,"body":"    StrBlob b1;                                  // line1\r\n    {                                                  // line2\r\n        StrBlob b2 = {\"a\", \"an\", \"the\"};// line3\r\n        b1 = b2;                                  // line4\r\n        b2.push_back(\"about\");          // line5\r\n    }                                                  // line6\r\n我得理解是：在第一行，b1的计数是1。第三行，b2的计数是1。第四行，b1在等号左边所以递减，变成0所以销毁了，b2在等号右边所以递增变成2。但答案中b1好像并未被销毁。请我我哪里理解错了？"}}