dangling object

基本解釋

A dangling alias occurs when two classes each think (mistakenly) that they hold the only writeable reference to a given object.
當(dāng)兩個(gè)類都（錯(cuò)誤地）認(rèn)為自己保存有對(duì)給定對(duì)象的惟一可寫的引用時(shí)，就會(huì)出現(xiàn)懸空指針。
To avoid dangling pointers (the dangerous situation where a block of memory is freed but a pointer still references it), you must delete the object only after the last reference is released.
為了避免懸空指針（一種危險(xiǎn)的情況，即一塊內(nèi)存已經(jīng)被釋放了，而一個(gè)指針還在引用它），必須在最后的引用釋放之后才刪除對(duì)象。