1.插在链表开头
新的节点插入到链表的开头，需要将新节点的指针指向链表的首节点，并将链表的首节点设为新节点。
New->next = Pointer;
Head = New;
2.插在链表中间
新的节点插入到链表的中间，如果我们找到Pointer节点，则需要将新节点的指针指向Pointer节点的指针(即下一个节点)，但不能让链表断裂。所以第一步必须将新节点的指针指向Pointer节点的指针，第二步再讲Pointer节点的指针指向新节点。
New->next = Pointer->next;
Pointer->next = New;
3,插在链表尾端
新的节点插入到链表的尾端(Pointer节点)，所以第一步必须将新节点的指针指向Pointer节点的指针(NULL)，第二步再将Pointer节点的指针指向新节点
New->next = Pointer->next;
Pointer->next = New;
示例：设计一个链表内节点插入的程序。
#include <stdio.h> #include <stdlib.h> #define MAX 10 struct List { int number; int total; struct List *next; }; typedef struct List Node; typedef Node *Link; int data[2][MAX] = {1, 3, 5, 7, 2, 4, 6, 8, 9, 0, 15, 35, 20, 23, 33, 45, 55, 56, 15, 10}; /********************** * 插入节点至链表内 **********************/ Link insert_list(Link head, Link new, int key) { Link pointer; pointer = head; while(1) { if(pointer == NULL) //插在首节点 { new->next = head; head = new; break; } if(pointer->number == key) //插在链表中间或尾端 { new->next = pointer->next; pointer->next = new; break; } pointer = pointer->next; //往下一个节点 } return head; } /********************** * 释放链表 *********************/ Link free_list(Link head) { Link pointer; while(head != NULL) { pointer = head; head = head->next; free(pointer); } } /********************** * 输出链表 *********************/ Link print_list(Link head) { Link pointer; //节点声明 pointer = head; //pointer指针设为首节点 while(pointer != NULL) { printf("[%d, %d]", pointer->number, pointer->total); pointer = pointer->next; } printf("\n"); } /********************** * 建立链表 *********************/ Link create_list(Link head) { Link new; //节点声明 Link pointer; int i; head = (Link)malloc(sizeof(Node)); //分配内存 if(head == NULL) { printf("Memory allocate failure!\n"); } else { head->number = data[0][0]; //定义首节点 head->total = data[1][0]; head->next = NULL; pointer = head; //将pointer指针设为首节点 for(i = 1; i < MAX; ++i) { new = (Link)malloc(sizeof(Node)); new->number = data[0][i]; new->total = data[1][i]; new->next = NULL; pointer->next = new; //将新节点串联在原列表尾端 pointer = new; //列表尾端节点为新节点 } } return head; } int main() { Link head; //节点声明 Link new; int key = 0; head = create_list(head); //建立链表 if(head != NULL) { print_list(head); while(1) { printf("Input 0 to exit!\n"); new = (Link)malloc(sizeof(Node)); //分配内存 printf("Please input the data number: "); scanf("%d", &new->number); if(new->number == 0) //输入0时结束 break; printf("please input the data total: "); scanf("%d", &new->total); printf("Please input the data number for insert: "); scanf("%d", &key); head = insert_list(head, new, key); //调用插入节点接口 print_list(head); //打印链表 } free_list(head); //释放链表 } return 0; }
