C语言如何建立链表并实现增删查改详解

#include <stdio.h>
#include <stdlib.h>

typedef struct {
 int *head;
 int length;
 int capacity;
} Toslist; //Toslist类型


//初始化顺序表
Toslist initSeqlist() {
 Toslist list;
 list.length = 0;
 list.capacity = 5;
 list.head = (int *)malloc(10 * sizeof(int));

 if (!list.head)
 {
 printf("初始化失败！\n");
 exit(0);
 }
 return list;
}

//打印顺序表
void displayList(Toslist list) {
 for (int i = 0; i < list.length; i++) {
 printf("%d ", list.head[i]);
 }
 printf("\n");
}

//插入元素
Toslist add(Toslist list, int elem, int pos) {
 if (list.length == list.capacity) {
 int *temp = (int *)realloc(list.head, (list.capacity + 1) * sizeof(int));//判断空间是否足够，不够就另建链表

//不直接用head而引入temp的作用：防止空间分配失败导致head失去原来的链表
 if (!temp) {
  list.head = temp;
  list.capacity += 1;
 }
 }

 //插入位置及以后的元素后移

 for (int i = list.length - 1; i >= pos; i--) {
 list.head[i + 1] = list.head[i];
 }
 list.head[pos] = elem;
 list.length ++;
 return list;

 if (pos > list.length || pos < 0)
 printf("插入位置错误！\n");
 return list;
}

//删除元素
Toslist delete(Toslist list, int pos) {

 for (int i = pos; i < list.length - 1; i++) {
 list.head[i] = list.head[i + 1];
 }

 list.length--;

 return list;

 if (pos < 0 || pos > list.length) {
 printf("删除位置有误！\n");
 return list;
 }
}

//查
int search(Toslist list, int elem) { //elem是查找的元素
 //顺序查找
 for (int i = 0; i < list.length; i++) {
 if (elem == list.head[i]) {
  return i;
 }
 }
 return 0;
}

//改
Toslist modify(Toslist list, int elem, int val) { //val是要替换它的元素
 int pos = search(list, elem); //获取要替换元素的位置
 list.head[pos] = val;
 return list;
}

int main() {
 Toslist list = initSeqlist();
 int Addpos = -1, Addnum, Delpos, Serachnum,Modifynum;

 printf("请输入5个整数元素\n");

 for (int i = 0; i < 5; i++) {
 scanf("%d", &list.head[i]);
 list.length++;
 }

 printf("顺序表中的元素有：\n");
 displayList(list);

 //插入元素
 printf("要在哪个元素后插入元素？\n");
 while (Addpos < 0 || Addpos > list.length) {
 scanf("%d", &Addpos);

 if (Addpos < 0 || Addpos > list.length)
  printf("请输入正确的位置！\n");
 };

 printf("请输入需要插入的元素：\n"); scanf("%d", &Addnum);
 printf("在顺序表的第%d个元素后插入元素%d得到\n", Addpos, Addnum);
 list = add(list, Addnum, Addpos);

 displayList(list);


 //删除元素
 printf("要删除顺序表下标顺序中哪个元素？\n"); scanf("%d", &Delpos);
 printf("删除后得到：\n");

 list = delete(list, Delpos);
 displayList(list);


 //查找
 printf("请输入需要查找的元素\n"); scanf("%d", &Serachnum);

 int pos = search(list, Serachnum);
 if(pos)
 printf("元素%d的位置为第%d个\n", Serachnum, pos+1);
 if(!pos){
 printf("表中无该元素\n");
 }


 //修改
 printf("请输入需要修改的元素：\n");scanf("%d",&Serachnum);
 printf("请输入要替换的数：\n");scanf("%d",&Modifynum);
 printf("将%d修改为%d得到：\n", Serachnum, Modifynum);
 list = modify(list, Serachnum, Modifynum);
 displayList(list);

 free(list.head);
 list.head = NULL;

 return 0;
}