链表的实现

#include<stdio.h>
#include<stdlib.h>
#define N 10

typedef struct node {
    int val;
    struct node *next;
} link,*plink;
int i=0,j=0,a[N]={0,1,2,3,4,5,6,7,8,9};

link *make_node(int n)
{
    link *p=NULL;
        if ((p = (link *) malloc(sizeof(link))) == NULL) {
            printf("error!");
            return NULL;
        }
        p->next = NULL;
        p->val=n;
        return p;
}
/*在头插入*/
void insert1(plink *head,link* p)
{
    
    p ->next=*head;
        *head=p;
}
/*在尾插入*/
 void insert2(plink *head,link*p)
{
    plink s=*head;
    if(*head==NULL)
     *head=p;
    else
    {
        while(s->next)
        s = s->next;
        s->next=p;

    }
} 
/*查巡一个*/
link* serach(plink head,int key){

        plink p;
    for (p = head; p; p = p->next)
        if (p->val == key)
        return p;
        return NULL;
}
/*遍历*/
void traverse(void (*visit)(plink),plink head)

{
        plink p;
    for (p = head; p; p = p->next)
                visit(p);
}
void visit(plink p)
{
printf("%4d",p->val);
}
/*删除*/
void delete(plink *head,plink p)

{
    plink pre;
        if (p == *head)
        {
            *head = p->next;
            return;
        }
    for (pre = *head; pre; pre = pre->next)
        if (pre->next == p)
        {
            pre->next = p->next;
            return;
        }

}
/*释放*/
void destroy(plink *head)

{
        plink q, p = *head;
            *head = NULL;
                while (p)
                {
                q = p;
                p = p->next;
                free_node(q);
                }
}

free_node(link *p)

{
    if (p)
        free(p);
}

int main(int argc, char *argv[]) {
        
    link *head=NULL, *p=NULL, *s=NULL;
    for (i = 0; i<N; i++)
    insert1(&head,make_node(a[i]));
    insert2(&head,make_node(a[i]));
    plink f=head;
    while(head){
        printf("%4d",head->val);
            head=head->next;
        }
            printf("\n");
    printf("%d\n",serach(f,5)->val);
        traverse(visit,f);
        delete(&f,serach(f,5));
        printf("\n");
        destroy(&f);
        
        while(f)
        {
        printf("%4d",f->val);
            f=f->next;
        
        }
        free_node(p);
}