C语言数据结构学习（3）：双链表

       双向链表也叫双链表，是链表的一种，它的每个数据结点中都有两个指针，分别指向直接后继和直接前驱。所以，从双向链表中的任意一个结点开始，都可以很方便地访问它的前驱结点和后继结点。一般我们都构造双向循环链表。

 
typedef struct DoubleLinkedNode{
    char data;
    struct DoubleLinkedNode *previous;    
    struct DoubleLinkedNode *next;        
}DLNode,*DLNodePtr;

 
DLNodePtr initLinkList(){
    DLNodePtr tempHeader=(DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
    tempHeader->data='';
    tempHeader->previous=NULL;
    tempHeader->next=NULL;
    return tempHeader;
}

 
void printList(DLNodePtr paraHeader){
    DLNodePtr p=paraHeader->next;
    while(p!=NULL){
        printf("%c",p->data);
        p=p->next;
    }
    printf("rn");
}

 
void insertElement(DLNodePtr paraHeader,char paraChar,int paraPosition){
    DLNodePtr p,q,r;
    
    p=paraHeader;
    for(int i=0;inext;
        if(p==NULL){
            printf("The position %d is beyond the scope of the list.rn",paraPosition);
            return;
        }
    }
    
    q=(DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
    q->data=paraChar;
    
    r=p->next;
    q->next=p->next;
    q->previous=p;
    p->next=q;
    if(r!=NULL){
        r->previous=q;
    }
}

 
void deleteElement(DLNodePtr paraHeader,char paraChar){
    DLNodePtr p,q,r;
    p=paraHeader;
 
    while((p->next!=NULL)&&(p->next->data!=paraChar)){
        p=p->next;
    }
    
    if(p->next==NULL){
        printf("The char '%c' does not exist.rn",paraChar);
        return;
    }
 
    q=p->next;
    r=q->next;
    p->next=r;
    if(r!=NULL){
        r->previous=p;
    }
 
    free(q);
}

 
void basicAddressTest(){
    DLNode tempNode1,tempNode2;
    
    tempNode1.data=4;
    tempNode1.next=NULL;
 
    tempNode2.data=6;
    tempNode2.next=NULL; 
 
    printf("The first node :%d,%d,%drn",&tempNode1,&tempNode1.data,&tempNode1.next);
    printf("The second node :%d,%d,%drn",&tempNode2,&tempNode2.data,&tempNode2.next);
 
    tempNode1.next=&tempNode2;
}

 
void insertDeleteTest(){
    
	DLNodePtr tempList=initLinkList();
    printList(tempList);
 
    insertElement(tempList,'H',0);
    insertElement(tempList,'e',1);
    insertElement(tempList,'l',2);
    insertElement(tempList,'l',3);
    insertElement(tempList,'o',4);
    insertElement(tempList,'!',5);
    printList(tempList);
 
    deleteElement(tempList,'e');
    deleteElement(tempList,'a');
    deleteElement(tempList,'o');
    //printf("YESn");
    printList(tempList);
 
    insertElement(tempList,'o',1);
    printList(tempList);
}
 

运行结果：

#include 
#include 


typedef struct DoubleLinkedNode{
	char data;
	struct DoubleLinkedNode *previous;
	struct DoubleLinkedNode *next;
} DLNode, *DLNodePtr;


DLNodePtr initLinkList(){
	DLNodePtr tempHeader = (DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
	tempHeader->data = '';
	tempHeader->previous = NULL;
	tempHeader->next = NULL;
	return tempHeader;
}// Of initLinkList


void printList(DLNodePtr paraHeader){
	DLNodePtr p = paraHeader->next;
	while (p != NULL) {
		printf("%c", p->data);
		p = p->next;
	}// Of while
	printf("rn");
}// Of printList


void insertElement(DLNodePtr paraHeader, char paraChar, int paraPosition){
	DLNodePtr p, q, r;

	// Step 1. Search to the position.
	p = paraHeader;
	for (int i = 0; i < paraPosition; i ++) {
		p = p->next;
		if (p == NULL) {
			printf("The position %d is beyond the scope of the list.", paraPosition);
			return;
		}// Of if
	} // Of for i

	// Step 2. Construct a new node.
	q = (DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
	q->data = paraChar;

	// Step 3. Now link.
	r = p->next;
	q->next = p->next;
	q->previous = p;
	p->next = q;
	if (r != NULL) {
		r->previous = q;
	}// Of if
}// Of insertElement


void deleteElement(DLNodePtr paraHeader, char paraChar){
	DLNodePtr p, q, r;
	p = paraHeader;

	// Step 1. Locate.
	while ((p->next != NULL) && (p->next->data != paraChar)){
		p = p->next;
	}// Of while

	// Step 2. Error check.
	if (p->next == NULL) {
		printf("The char '%c' does not exist.rn", paraChar);
		return;
	}// Of if

	// Step 3. Change links.
	q = p->next;
	r = q->next;
	p->next = r;
	if (r != NULL) {
		r->previous = p;
	}// Of if

	// Step 4. Free the space.
	free(q);
}// Of deleteElement


void insertDeleteTest(){
	// Step 1. Initialize an empty list.
	DLNodePtr tempList = initLinkList();
	printList(tempList);

	// Step 2. Add some characters.
	insertElement(tempList, 'H', 0);
	insertElement(tempList, 'e', 1);
	insertElement(tempList, 'l', 2);
	insertElement(tempList, 'l', 3);
	insertElement(tempList, 'o', 4);
	insertElement(tempList, '!', 5);
	printList(tempList);

	// Step 3. Delete some characters (the first occurrence).
	deleteElement(tempList, 'e');
	deleteElement(tempList, 'a');
	deleteElement(tempList, 'o');
	printList(tempList);

	// Step 4. Insert to a given position.
	insertElement(tempList, 'o', 1);
	printList(tempList);
}// Of appendInsertDeleteTest


void basicAddressTest(){
	DLNode tempNode1, tempNode2;

	tempNode1.data = 4;
	tempNode1.next = NULL;

	tempNode2.data = 6;
	tempNode2.next = NULL;

	printf("The first node: %d, %d, %drn",
		&tempNode1, &tempNode1.data, &tempNode1.next);
	printf("The second node: %d, %d, %drn",
		&tempNode2, &tempNode2.data, &tempNode2.next);

	tempNode1.next = &tempNode2;
}// Of basicAddressTest


void main(){
	insertDeleteTest();
	basicAddressTest();
}// Of main