我试图按分数对节点进行排序。 我不知道我有什么错误

#include #include #include struct student{ char firstname[20]; char lastname[20]; double grade; char zipcode[10]; struct student *next; }; void display(struct student *first) { while (first != NULL) { printf("\nFirst name: %s", first->firstname); printf("\tLast name: %s", first->lastname); printf("\tGrade: %.2f", first->grade); printf("\t ZipCode: %s", first->zipcode); first = first->next; } } /*void add_Record(struct student *first) { char r[20]; struct student *t; t = first; while (t != NULL) { if (t == NULL) { first = (struct student*)malloc(sizeof(struct student)); printf("\nEnter the first name of the student:"); scanf("%s", first->firstname); printf("\nEnter the last name of the student:"); scanf("%s", first->lastname); printf("\nEnter the score of the student:"); scanf("%lf", &first->grade); printf("\nEnter the zipcode of the student:"); scanf("%s", first->zipcode); } } } void del() { struct student *back, *t, *k; char r[10]; int flag = 0; printf("\nEnter the last name of student you want to delete:"); scanf("%s", r); if (strcmpi(r, first->lastname) == 0) { first = first->next; flag = 1; } else { back = first; k = first->next; while (k != NULL) { if (strcmpi(r, k->lastname) == 0) { back->next = k->next; flag = 1; break; } } } if (flag == 0) printf("\nThe element not found!!!"); } */ void search(struct student *first) { char r[10]; int flag = 0; printf("\nEnter the zipcode you want to search:"); scanf("%s", r); struct student *t; t = first; while (t != NULL) { if (strcmp(r, t->zipcode) == 0) { printf("\nFirst name: %s", t->firstname); printf("\tLast name: %s", t->lastname); printf("\tGrade: %.2f", t->grade); printf("\t ZipCode: %s", t->zipcode); flag = 1; break; }t = t->next; } if (flag == 0) printf("\nThe zipcode not in database!!"); } void sort(struct student *first) { struct student *temp; temp = NULL; while (first != NULL) { if (first-> grade > first->next->grade) { strcpy(temp->firstname, first->firstname); strcpy(temp->lastname, first->lastname); temp->grade = first->grade; strcpy(temp->zipcode, first->zipcode); strcpy(first->firstname, first->next->firstname); strcpy(first->lastname, first->next->lastname); first->grade = first->next->grade; strcpy(first->zipcode, first->next->zipcode); strcpy(first->next->firstname, temp->firstname); strcpy(first->next->lastname, temp->lastname); first->next->grade = temp->grade; strcpy(first->next->zipcode, temp->zipcode); break; } } printf("\nThe sorted record by score are: \n"); display(first); } int main(void) { struct student *first = NULL, *last = NULL; struct student *temp; int n; printf("\nEnter the number of student:"); scanf("%d", &n); int i; for (i = 0; i firstname); printf("\nEnter the last name of the student:"); scanf("%s", temp->lastname); printf("\nEnter the grade of the student:"); scanf("%lf", &temp->grade); printf("\nEnter the zipcode of the student:"); scanf("%s", temp->zipcode); temp->next = first; first = temp; } int o; o = 1; while (o != 0) { printf("\nMENU\n"); printf("\nEnter 1 for displaying database."); printf("\nEnter 2 for inserting an record."); printf("\nEnter 3 for deleting a record by lastname."); printf("\nEnter 4 for searching a record by zipcode."); printf("\nEnter 5 for sorting record by score."); printf("\nEnter 0 for exit!"); printf("\nEnter the choice:"); scanf("%d", &o); switch (o) { case 1:display(first); break; /*case 2:insertafter(*first); break; case 3:del(); break;*/ case 4:search(first); break; case 5: sort(first); break; case 0:exit(0); break; default:printf("\nYou have entered a wrong choice!!!"); } } } 

问题是我如何按分数对分数进行排序。 我的代码看似正确但不起作用。 我做了一个临时结构，并尝试交换值，但它不起作用。 我做错了吗？ 或者我的所有代码都错了？

Answer 1

这是问题的两个答案

首先，通过对它们进行冒泡排序来对节点链表中的节点进行排序，重新排列链表

第二个遍历链表，将每个指针复制到一个数组中，然后使用结构级成员对数组进行排序，链表保持不变

 #include #include #include  #define SWAP(T,x,y) {T *p = &(x); T *q = &(y); T z = *p; *p = *q; *q = z;} struct student{ char firstname[20]; char lastname[20]; double grade; char zipcode[10]; struct student *next; }; struct student *head=NULL; void add(char *f, char *s, double score) { struct student *a; a=(struct student*)malloc(sizeof(struct student)); strcpy(a->firstname,f); strcpy(a->lastname,s); a->grade = score; a->next = head; head = a; } void printout(char *label) { struct student *node; printf("%s\n",label); for(node=head; node !=NULL; node=node->next) { printf("%s %s %f\n", node->firstname, node->lastname, node->grade); } } int main(int argc, char ** argv){ int mark=8; struct student *walk, *prev; add("Bob","Smith",10); add("Eric","Von Däniken",90); add("Morris","Minor",91); add("Master","Bates",9); add("Zoe","Bodkin",20); add("Mary","Pippin",30); /* bubble sort */ printout("before"); prev=head; while(mark) { mark=0; for(walk=head; walk != NULL; walk=walk->next) { if (walk->next && walk->grade > walk->next->grade) { /* printf("swapping %s %s\n", walk->firstname, walk->next->firstname); */ mark=1; if (walk == head) { struct student *v2=walk->next; struct student *v3=walk->next->next; SWAP(struct student *, v3->next, v2->next); SWAP(struct student *, head, v3->next); walk = v3; } else { struct student *v1=prev; struct student *v2=walk; struct student *v3=walk->next; SWAP(struct student *, v3->next, v2->next); SWAP(struct student *, v1->next, v3->next); walk = v3; } } prev=walk; } } printout("after"); return 0; } 

第二个版本，使用qsort，保留链表顺序

 #include #include #include  struct student{ char firstname[20]; char lastname[20]; double grade; char zipcode[10]; struct student *next; }; struct student *head=NULL; size_t nodecount=0; void add(char *f, char *s, double score) { struct student *a; a=(struct student*)malloc(sizeof(struct student)); strcpy(a->firstname,f); strcpy(a->lastname,s); a->grade = score; a->next = head; head = a; nodecount++; } static int cmpgrade(const void *p1, const void *p2) { struct student *g1, *g2; g1=*(struct student **)p1; g2=*(struct student **)p2; return g1->grade > g2->grade; } int main(int argc, char ** argv){ int i; struct student *walk,**sa, **sap; add("Bob","Smith",10); add("Eric","Von Däniken",90); add("Morris","Minor",91); add("Master","Bates",9); add("Zoe","Bodkin",20); add("Mary","Pippin",30); /*copy into array of pointers*/ sa=calloc(sizeof (struct student*), nodecount); sap=sa; for(walk=head; walk != NULL; walk=walk->next) { *sap = walk; sap++; } printf("before\n"); for (i=0; i< nodecount; i++) { printf("%s %s %f\n", sa[i]->firstname, sa[i]->lastname, sa[i]->grade); } /* qsort */ qsort(sa, nodecount, sizeof (struct student *), cmpgrade); printf("after\n"); for (i=0; i< nodecount; i++) { printf("%s %s %f\n", sa[i]->firstname, sa[i]->lastname, sa[i]->grade); } return 0; }