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循环单向链表只是在单向链表的基础上使尾结点指向头结点。因为每次插入结点，新结点都是指向上一个结点当前的下一个结点。因此在单向链表的基础上，我们使头结点指向自身即可。
因此只需要在以前的博文单链表代码中的构造函数初始化的时候，加上一行代码，便做到了循环：m_pHeadNode->SetNext(m_pHeadNode);
//CircularSinglyLink.h#pragma once#include#include template class Node{public: Node(Node * pNext = NULL, ElemType* pData = NULL); ElemType const& GetData() const; void SetData(ElemType val) ; Node * const& GetNext() const; void SetNext(Node * val);private: ElemType* m_pData; Node * m_pNext;};template class CircularSinglyLink{public: CircularSinglyLink(); unsigned int const& GetLength() const; bool Insert(ElemType elem, unsigned int pos); bool InsertByPosNode(ElemType elem, Node * posNode, Node ** RetInsetNode = NULL); bool Delete(unsigned int pos, ElemType* elem); bool Search(unsigned int pos, ElemType* elem) const; bool Visit(ElemType* elem, const unsigned int& pos) const; bool Empty(); Node * HavaHeadNode();private: Node * m_pHeadNode; unsigned int m_length;};//————————————————————————————————//Node类的实现template Node ::Node(Node * pNext /*= NULL*/, ElemType* pData /*= NULL*/) :m_pNext(pNext),m_pData(pData){}template void Node ::SetNext(Node * val){ m_pNext = val;}template Node * const& Node ::GetNext() const{ return m_pNext;}template void Node ::SetData(ElemType val){ m_pData = val;}template ElemType const& Node ::GetData() const{ return *m_pData;}//————————————————————————————————//SinglyLink类实现template CircularSinglyLink ::CircularSinglyLink() :m_pHeadNode(new Node ()),m_length(0){ m_pHeadNode->SetNext(m_pHeadNode);}template bool CircularSinglyLink ::InsertByPosNode(ElemType elem, Node * posNode, Node ** RetInsetNode /*= NULL*/){ Node * insertNode = new Node (posNode->GetNext(),new ElemType(elem)); posNode->SetNext(insertNode); ++m_length; *RetInsetNode = insertNode; return true;}template bool CircularSinglyLink ::Insert(ElemType elem, unsigned int pos){ if (pos > GetLength() || pos < 0) { assert(false && "Error: SinglyLink's insert pos is out of range!\n"); return false; } for(Node * pCurrentNode = m_pHeadNode; pCurrentNode != NULL; pCurrentNode = pCurrentNode->GetNext()) { if (pos-- == 0) { Node * insertNode = new Node (pCurrentNode->GetNext(),new ElemType(elem)); pCurrentNode->SetNext(insertNode); ++m_length; return true; } } assert(false && "Error: SinglyLink Insert failed for unknow reason!"); return false;}template bool CircularSinglyLink ::Delete(unsigned int pos, ElemType* elem){ if (pos >= GetLength() || pos < 0) { assert(false && "Error: SinglyLink's delete pos is out of range!\n"); } for(Node * pCurrentNode = m_pHeadNode; pCurrentNode != NULL; pCurrentNode = pCurrentNode->GetNext()) { if (pos-- == 0) { Node * deleteNode = pCurrentNode->GetNext(); pCurrentNode->SetNext(deleteNode->GetNext()); *elem = deleteNode->GetData(); delete deleteNode; --m_length; return true; } } assert(false && "Error: SinglyLink pos delete failed for unknow reason!"); return false;}template unsigned int const& CircularSinglyLink ::GetLength() const{ return m_length;}template bool CircularSinglyLink ::Search(unsigned int pos, ElemType* elem) const{ if (pos >= GetLength() || pos < 0) { assert(false && "Error: SinglyLink's search pos is out of range!\n"); } for(Node * pCurrentNode = m_pHeadNode; pCurrentNode != NULL; pCurrentNode = pCurrentNode->GetNext()) { if (pos-- == 0 && (pCurrentNode->GetNext() != NULL) ) { *elem = pCurrentNode->GetNext()->GetData(); return true; } } return false;}template bool CircularSinglyLink ::Visit(ElemType* elem, const unsigned int& pos) const{ if (pos >= GetLength() || pos < 0) { return false; } return Search(pos,elem);}template bool CircularSinglyLink ::Empty(){ return !m_length;}template Node * CircularSinglyLink ::HavaHeadNode(){ return m_pHeadNode;}
//Util.h#pragma oncenamespace Util{ template void PrintMemory(const T& dateStruct, unsigned int size) { cout << "PrintMemory: "; for (int i = 0; i != size; i++) { ElemType tempElem; if (!dateStruct.Visit(&tempElem,i)) { printf("\n"); return; } printf("%d ",tempElem); } printf("\n"); }} //main.cpp#include "Util.h"#include "CircularSinglyLink.h"#includeusing namespace std;typedef int ElemType;int main(){ CircularSinglyLink testCircularSinglyLink; cout << "testCircularSinglyLink is " << (testCircularSinglyLink.Empty() ? "Empty." : "Not Empty.") << endl; Util::PrintMemory(testCircularSinglyLink,testCircularSinglyLink.GetLength()); for (int i = 0; i != 5; i++) { testCircularSinglyLink.Insert(i+1,i); cout << "\nInsert:" << i << endl; cout << "testCircularSinglyLink is " << (testCircularSinglyLink.Empty() ? "Empty." : "Not Empty.") << endl; Util::PrintMemory(testCircularSinglyLink,testCircularSinglyLink.GetLength()); } for (int i = 0; i != 2; i++) { ElemType tempElem; testCircularSinglyLink.Delete(i,&tempElem); cout << "\nDelete:" << tempElem << endl; cout << "testCircularSinglyLink is " << (testCircularSinglyLink.Empty() ? "Empty." : "Not Empty.") << endl; Util::PrintMemory(testCircularSinglyLink,testCircularSinglyLink.GetLength()); } return 0;}
testCircularSinglyLink is Empty.
PrintMemory:Insert:0
testCircularSinglyLink is Not Empty. PrintMemory: 1Insert:1
testCircularSinglyLink is Not Empty. PrintMemory: 1 2Insert:2
testCircularSinglyLink is Not Empty. PrintMemory: 1 2 3Insert:3
testCircularSinglyLink is Not Empty. PrintMemory: 1 2 3 4Insert:4
testCircularSinglyLink is Not Empty. PrintMemory: 1 2 3 4 5Delete:1
testCircularSinglyLink is Not Empty. PrintMemory: 2 3 4 5Delete:3
testCircularSinglyLink is Not Empty. PrintMemory: 2 4 5
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