C语言数据结构：单向链表

线性表是最常用且最简单的一种数据结构。一个线性表是多个数据元素的序列，数据元素的具体含义可以根据自己的情况实现，而一个数据元素又可以由若干个数据项组成。下面用单向链表的方式实现线性表，数据元素仅有一个int型变量和指向下一节点的数据指针。程序的功能有插入，删除，修改，判断相等的数据是否存在，计算链表长度，根据位置返回节点值，排序和就地逆置。

#include <stdio.h>#include <stdlib.h>typedef struct _listNode{    int value;    struct _listNode * next;}listNode, *pListNode;pListNode List_create(int);void List_destroy(pListNode head);int List_getListLength(pListNode head);int List_getNode(pListNode head, int pos, pListNode myNode);// 0 presents no node at posint List_isExisting(pListNode head, pListNode myNode);// 0 presents not exist, positive number is the position of the same-value nodepListNode List_insert(pListNode head, int pos, pListNode myNode);// insert node at pospListNode List_delete(pListNode head, int pos, pListNode myNode);void List_union(pListNode head1, pListNode head2);// head1 is the new listvoid List_modify(pListNode head, int pos, pListNode myNode);// replace node contents at pos with myNodepListNode List_ascendingSort(pListNode head);pListNode List_localReverse(pListNode head);void List_displayAll(pListNode head);int main(){    // these are test nodes    pListNode insert0 = List_create(0);    pListNode insert_1 = List_create(-1);    pListNode insert2 = List_create(2);    pListNode insert9 = List_create(9);    // head node    pListNode head = List_create(5);    List_displayAll(head);    // test insert operation    // insert before head    head = List_insert(head, 1, insert0);    printf("insert 0 before head.\n");    List_displayAll(head);    // insert between    head = List_insert(head, 2, insert_1);    printf("insert -1 at pos 2.\n");    List_displayAll(head);    // insert at tail    head = List_insert(head, 4, insert2);    printf("insert 2 at tail.\n");    List_displayAll(head);    head = List_insert(head, 4, insert9);    printf("insert 9 at pos 4.\n");    List_displayAll(head);    printf("\n");    // test get length operation    int len = List_getListLength(head);    printf("list length is: %d\n\n", len);    // test get node operation    pListNode temp = List_create(0);    printf("temp node value is: %d\n", temp->value);    List_getNode(head, 2, temp);    printf("after get node operation with pos 2, temp value is: %d\n", temp->value);    printf("before modify:\n");    List_displayAll(head);    printf("after modify with value %d at pos 1:\n", temp->value);    List_modify(head, 1, temp);    List_displayAll(head);    printf("\n");    // test is existing operation    int pos = List_isExisting(head, temp);    printf("is existing operation with value -1, result is: %d\n\n", pos);    // test delete operation    // delete head    head = List_delete(head, 1, temp);    printf("delete head.\n");    List_displayAll(head);    head = List_delete(head, 2, temp);    printf("delete node with pos 2.\n");    List_displayAll(head);    head = List_delete(head, List_getListLength(head), temp);    printf("delete tail.\n");    List_displayAll(head);    printf("\n");    // test union operation    pListNode head1 = List_create(10);    pListNode node = List_create(21);    head1 = List_insert(head1, 1, node);    printf("list 2 is: \n");    List_displayAll(head1);    printf("after union operation:\n");    List_union(head, head1);    List_displayAll(head);    printf("\n");    // test ascending operation    printf("after ascending operation:\n");    head = List_ascendingSort(head);    List_displayAll(head);    printf("\n");    // test local reverse operation    printf("after local reverse operation:\n");    head = List_localReverse(head);    List_displayAll(head);    printf("\n");    // test destroy operation    printf("after destroy operation:\n");    List_destroy(head);    printf("head value is invalid: %d\n\n", head->value);    system("pause");    return 0;}pListNode List_create(int value){    pListNode head = (pListNode)malloc(sizeof(listNode));    if(head == NULL){        printf("Have no space for head node.\n");    }    head->value = value;    head->next = NULL;    return head;}void List_destroy(pListNode head){    pListNode previous = NULL, current = head;    while(current != NULL){        previous = current;        current = current->next;        free(previous);    }}int List_getListLength(pListNode head){    int count = 0;    pListNode current = head;    while(current != NULL){        current = current->next;        count++;    }    return count;}// 0 presents no node at posint List_getNode(pListNode head, int pos, pListNode myNode){    if(pos < 1 || pos >= List_getListLength(head)){        printf("wrong position when get node.\n");        return 0;    }    int i = 1;    pListNode current = head;    while(i != pos){        current = current->next;        i++;    }    myNode->value = current->value;    myNode->next = NULL;    return 1;}// 0 presents not exist, positive number is the position of the same-value nodeint List_isExisting(pListNode head, pListNode myNode){    int pos = 0, tag = 0;    pListNode current = head;    while(current != NULL){        pos++;        if(current->value == myNode->value){            tag = 1;            break;        }        current = current->next;    }    if(tag == 0){        pos = 0;    }    return pos;}// insert myNode at pospListNode List_insert(pListNode head, int pos, pListNode myNode){    if(pos < 1 || pos > List_getListLength(head)+1){        printf("wrong position when insert node.\n");        return head;    }    // insert before head    if(pos == 1){        myNode->next = head;        head = myNode;        return head;    }    // insert into the list    int i = 1;    pListNode previous = NULL, current = head;    while(current != NULL){        previous = current;        current = current->next;        i++;        if(i == pos){            break;        }    }    previous->next = myNode;    myNode->next = current;    return head;}pListNode List_delete(pListNode head, int pos, pListNode myNode){    if(pos < 1 || pos > List_getListLength(head)){        printf("wrong position when delete node.\n");        return head;    }    // judge if list is empty    if(head == NULL){        printf("list is empty, can't be delete.\n");        return head;    }    // delete head    pListNode current = head;    if(pos == 1){        head = head->next;        free(current);        return head;    }    // other situation    int i = 1;    for(i = 1; i < pos - 1; i++){        current = current->next;    }    pListNode deleteNode = current->next;    current->next = deleteNode->next;    myNode->value = deleteNode->value;    free(deleteNode);    return head;}// head1 is the new listvoid List_union(pListNode head1, pListNode head2){    if(head1 == NULL){        printf("parameter is type of NULL, exit.\n");        return;    }    pListNode current = head1;    for(; current->next != NULL; current = current->next);    current->next = head2;}// replace node contents at pos with myNodevoid List_modify(pListNode head, int pos, pListNode myNode){    if(head == NULL || myNode == NULL){        printf("head or node is type of NULL, exit.\n");        return;    }    if(pos < 1 || pos > List_getListLength(head)){        printf("wrong position when modify node.\n");        return;    }    int i = 1;    pListNode current = head;    for(; i < pos; i++, current = current->next);    current->value = myNode->value;}pListNode List_ascendingSort(pListNode head){    if(head == NULL){        printf("head is NULL.\n");        return head;    }    // bubble sort    pListNode current = head;    int temp = 0;    int i = 0, j = 0, k = List_getListLength(head);    for(i = 0; i < k; i++){        current = head;        for(j = 0; j < i; j++){            current = current->next;        }        for(j = i; j < k-1; j++){            if(current->value > current->next->value){                temp = current->value;                current->value = current->next->value;                current->next->value = temp;            }            current = current->next;        }    }    return head;}pListNode List_localReverse(pListNode head){    pListNode p = head, q = NULL;    head = NULL;    while(p){        q = p->next;        p->next = head;        head = p;        p = q;    }    return head;}void List_displayAll(pListNode head){    if(head == NULL){        printf("head is NULL, exit\n");        return;    }    pListNode current = head;    printf("list is: ");    for(; current != NULL; current = current->next){        printf("\t%d", current->value);    }    printf("\n");}

下面是测试结果

list is:        5insert 0 before head.list is:        0       5insert -1 at pos 2.list is:        0       -1      5insert 2 at tail.list is:        0       -1      5       2insert 9 at pos 4.list is:        0       -1      5       9       2list length is: 5temp node value is: 0after get node operation with pos 2, temp value is: -1before modify:list is:        0       -1      5       9       2after modify with value -1 at pos 1:list is:        -1      -1      5       9       2is existing operation with value -1, result is: 1delete head.list is:        -1      5       9       2delete node with pos 2.list is:        -1      9       2delete tail.list is:        -1      9list 2 is:list is:        21      10after union operation:list is:        -1      9       21      10after ascending operation:list is:        -1      9       10      21after local reverse operation:list is:        21      10      9       -1after destroy operation:head value is invalid: 7025048