在链表的友元类

朋友类是能够访问类中声明一个朋友的保护或私有变量codeprelang="c++"spanclass="code-keyword"class/spanA{ spanclass="code-keyword"private/span: spanclass="code-keyword"int/spana; spanclass="code-keyword"friend/spanspanclass="code-keyword"class/spanB;spanclass="code-comment"///spanspanclass="code-comment"ThisletsanycodeinclassBaccessanythingprivateinhere/span}; spanclass="code-keyword"class/spanB{ spanclass="code-keyword"public/span: spanclass="code-keyword"void/spanGetA(spanclass="code-keyword"const/spanA&object){ spanclass="code-keyword"return/spanobject.a;spanclass="code-comment"///spanspanclass="code-comment"ThiswouldusuallybeillegalbecauseA.aisprivate,butthisclassisafriendofA,soitisallowed/span }};/pre/code然而在一个链表，这不应该需要。链表的每个节点通常会是同一类
。安德鲁・布洛克