链表操作，涉及到链表首节点指针变动的函数，即使形参包含首节点指针，必须返回首节点指针，原因不得而知

 

  1 //链表操作，涉及到链表首节点指针变动的函数，即使形参包含首节点指针，必须返回首节点指针，原因不得而知
  2 # include<stdio.h>
  3 # include<stdlib.h>
  4 struct Student
  5 {
  6     int num;
  7     struct Student* next;
  8 };
  9 struct Student* p;
 10 int main()
 11 {
 12     struct Student*p1;
 13     int n;
 14     scanf("%d",&n);
 15 
 16     int len(struct Student*);
 17     struct Student* create(int);                                /*这里不能用void create(struct Student*,int);
 18                                                                  因为创建链表涉及到链表首元素指针的变动，会出现错误，原因未解；*/
 19     
 20     struct Student* insert(struct Student*,struct Student*,int); /*不能用void insert(struct Student*,struct Student*,int);
 21                                                                  往链首插元素会涉及到链表首节点指针变动，从而引发错误*/
 22                                                                 
 23     
 24     struct Student* del(struct Student*,int);                    /*不能用void del(struct Student*,int);
 25                                                                  删除链首插元素会涉及到链表首节点指针变动，从而引发错误*/
 26     void print(struct Student*);
 27 
 28     p=create(n);
 29     print(p);
 30     p1=(struct Student*)malloc(sizeof(Student));
 31     p1->num=15;
 32 
 33     p=insert(p,p1,0);
 34     print(p);
 35     p=del(p,23);
 36     print(p);
 37 
 38     return 0;
 39 }
 40 
 41 int len(struct Student *p)
 42 {
 43     struct Student *p1=p;
 44     int i=0;
 45     while(p)
 46     {
 47         i++;
 48         p=p->next;
 49     }
 50     return i;
 51 }
 52 
 53 struct Student*  create(int n)   /*这里不能用void create(struct Student*,int);
 54                                  因为创建链表涉及到链表首元素指针的变动，会出现错误，原因未解；*/
 55 {
 56     int i=0;
 57     struct Student*p1,*p2,*head;
 58     p1=(struct Student*)malloc(sizeof(Student));
 59     while(i<n)
 60     {
 61         i++;
 62         p1->num=i;
 63         if(i==1) head=p2=p1;
 64         else
 65         {
 66             p2->next=p1;
 67             p2=p1;
 68         }
 69         p1=(struct Student*)malloc(sizeof(Student));
 70     }
 71     free(p1);
 72     p2->next=NULL;
 73     p1=NULL;
 74     return head;
 75 }
 76 
 77 struct Student* insert(struct Student* p,struct Student*p1,int n) /*不能用void insert(struct Student*,struct Student*,int);
 78                                                                  往链首插元素会涉及到链表首节点指针变动，从而引发错误*/
 79 {
 80     struct Student*q;
 81     q=p;
 82     int i=1,j=len(p);
 83     if(n<0||n>j)
 84     {
 85         printf("输入错误\n");
 86     }
 87     else if(n==0)  //插到链头
 88     {
 89         p1->next=p;
 90         p=p1;
 91     }
 92     else
 93     {
 94         for(;i<n;i++,q=q->next);
 95         p1->next=q->next;
 96         q->next=p1;
 97         p1=NULL;
 98     }
 99     return p;
100 }
101 
102 struct Student* del(struct Student* p,int n)  /*不能用void del(struct Student*,int);
103                                                删除链首插元素会涉及到链表首节点指针变动，从而引发错误*/
104 {
105     struct Student*q,*r;
106     int i,j=len(p);
107     
108     if(n<1||n>j)
109     {
110         printf("输入错误\n");
111     }
112     
113     else if(n==1)
114     {
115         q=p;
116         p=p->next;
117         free(q);
118     }
119     
120     else
121     {
122         r=p;
123         q=r->next;
124         for(i=2;i<n;i++,q=q->next,r=r->next);
125         r->next=q->next;
126         free(q);
127     }
128     return p;
129 }
130 
131 
132 void print(struct Student* p)
133 {
134     int i=0;
135     while(p!=NULL)
136     {
137         i++;
138         printf("%5d",p->num);
139         if(i%10==0) printf("\n");
140         p=p->next;
141     }
142     printf("\n");
143 
144 }

运行结果：

 

posted @ 2020-03-20 12:18  kakusan  阅读(194)  评论(0)  编辑  收藏  举报