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 }
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