C链表小结

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

typedef struct node* point;

struct node{
   int data;
   point next;
};

typedef point LinkedList;

void initial(LinkedList* list);

int insertElem(int data,LinkedList list,int position);

int delElem(int position,LinkedList list);

void iteratorElem(LinkedList list);

int getElem(LinkedList list , int position);

int updateElem(LinkedList list, int position, int data);

bool isNull(LinkedList list);

int getLength(LinkedList list);


void initial(LinkedList* list){   //指向指针的指针，用于改变指针指向的指针指向的内存地址。
   *list = (LinkedList)malloc(sizeof(LinkedList));
   (*list)->next=NULL;   
}

int insertElem(LinkedList list,int position,int data){
   point p = list;
   int i = 0; //开始的，指向头结点，此节点的下标为0。p指向头结点位置
   while(p!=NULL&&i<position-1){ //获取position-1位置的point内存地址
   p = p->next;
   i++;//p指向线性表中第i个元素的地址
   }
   if(p == NULL){ //position-1位置不存在，就不能往列表中在插入position位置的值
   return NULL;
   }  
   point node = (point)malloc(sizeof(point));
   node->data = data;
   node->next=p->next;//注意顺序
   p->next = node;  
   return 1;
}

int delElem(int position,LinkedList list){
   point p = list;
   int i = 0;
   while(i<position-1&&p!=NULL){ //得到position-1位置的指针
   p=p->next;
   i++;
   }
   if(p == NULL){//该位置不存在，返回
    return NULL;
   }
   point temp = p->next;   
   p->next = temp->next; //删除节点操作
  // free(temp);//释放堆内存
   return 1;
}

void iteratorElem(LinkedList list){
   point p = list->next;
   int i = 0;
   printf("\n======================================================\n");
   while(p!=NULL){
   i++;
   printf("%d  =  %d\t",i,p->data);
   p=p->next;
   }
   printf("\n======================================================\n");
}

int getElem(LinkedList list , int position){
   point p = list;
   int i = 0;
   while(p!=NULL && i<position){
      p = p->next;
  i++;
   }
   if(p==NULL){
   return NULL;
   }
   return p->data;
}

int updateElem(LinkedList list, int position, int data){
point p = list;
int i = 0;
while(i<position&&p!=NULL){
p=p->next;
i++;
}
if(p==NULL){
return NULL;
}
p->data = data;
    return 1; 
}

bool isNull(LinkedList list){
point p = list->next;
if(p->next!=NULL)
return false;
else
return true;
}

int getLength(LinkedList list){
point p = list;
int  i=0;
while(p!=NULL){
p=p->next;
i++;
}
return i;
}





void main(void){
    LinkedList list = NULL;
initial(&list);
if(list == NULL){
printf("ssss");
}
int num ;
for(int i = 0;i<10;i++){
scanf("%d" , &num);
int result = insertElem(list,i+1,num);
if(result == NULL){
printf("%d insert error \n",num);
}
}
iteratorElem(list);
updateElem(list,5,100);
iteratorElem(list);
delElem(5,list);
delElem(9,list);
iteratorElem(list);
printf("\n%d",getLength(list));
printf("\n%d",getElem(list,3));
}