无法在C中按升序对链表进行排序
我正在尝试使用代码块编辑器在C上制作图书馆管理系统程序。
到目前为止，我已经成功地制作了图书馆图书的程序打印清单，包括其名称和作者的名字，但是当它询问我是否要按升序排列并按'y'时，它会再次打印相同的列表，但不按升序排列（我正在尝试使用冒泡排序算法进行排序）。
请相应地修改代码，并附上详细说明。
原始
：#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Node {
char name[50];
char author[50];
struct Node* next;
};
struct Node* head; // Global Variable
void Insert(char q[50], char r[50]);
void Print();
void bsort();
int main()
{
int n,i; //Local Variables
char x[50],y[50]; // Local Variables
char d;
head=NULL; //Initially head is null
printf("How many books you want to enter?: ");
scanf("%d",&n);
for (i=1; i<=n; i++) // Loop iterate the number of times we have books in quantity.
{
printf("Enter a Book name: ");
fflush(stdin); // To clear buffer memory
gets(x); // Same as scanf
printf("Author: ");
gets(y);
Insert(x,y);
}
Print();
printf("Do you want to sort the data in ascending order?(y/n): ");
scanf("%c",&d);
printf("Your pressed %c",d);
if (d=='y')
{
bsort();
Print();
}
else
printf("alright!");
return 0;
}
void Insert(char q[50], char r[50]) //Adding items at the end of linked list
{
struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
temp->next=NULL; // Since we are adding a node to the end, we are linking it to NULL.
strcpy(temp->name,q); // copying the contents of "q" to "temp->name"
strcpy(temp->author,r); // same
if(head==NULL)
{
head=temp;
}
else
{
struct Node* temp1 = head;
while(temp1->next!=NULL)
temp1=temp1->next;
temp1->next=temp;
}
}
void Print() //Traversing
{
printf("\n");
printf("The Library data is as follows: \n");
struct Node* temp=head;
printf("\n");
while(temp!=NULL)
{
printf("%25s",temp->name);
printf("%25s",temp->author);
temp=temp->next;
printf("\n");
}
}
void bsort() //Bubble Sort Algorithm to arrange Library data in Ascending Order
{
int count=1,k=1;
char temp3[50];
struct Node* i=head;
struct Node* j;
j=i->next;
while(i!=NULL)
{
i=i->next;
count++;
}
{
for (k=1; k=count-1; k++)
{
for (i=head; i<=NULL-k; i=i->next)
{
if(i->name>j->name)
{
strcpy(temp3,i->name);
strcpy(i->name,j->name);
strcpy(j->name,temp3);
}
j=j->next;
}
}
}
}
首次修改：
void bsort() //Bubble Sort Algorithm to arrange Library data in Ascending Order
{
int count=1,k=1;
char temp3[50];
struct Node* i=head;
struct Node* j;
j=i->next;
while(i!=NULL)
{
i=i->next;
count++;
}
for (k=1; k=count-1; k++)
{
for (i=head; i<=count-k; i=i->next)
{
if (strcmp(i->name,j->name)>0)
{
strcpy(temp3,i->name);
strcpy(i->name,j->name);
strcpy(j->name,temp3);
}
j=j->next;
}
}
}
第二次修改：
void bsort() //Bubble Sort Algorithm to arrange Library data in Ascending Order
{
int count=1,k=1;
char temp3[50];
struct Node* i=head;
struct Node* j;
j=i->next;
while(i!=NULL)
{
i=i->next;
count++;
}
for (k=1; k<=count-1; k++)
{
for (i=head; i<=count-k; i=i->next)
{
if (strcmp(i->name,j->name)>0)
{
strcpy(temp3,i->name);
strcpy(i->name,j->name);
strcpy(j->name,temp3);
}
j=j->next;
}
}
}
第三次修改
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Node {
char name[50];
char author[50];
struct Node* next;
};
struct Node* head; // Global Variable
void Insert(char q[50], char r[50]);
void Print();
void bsort_print();
int main()
{ int n,i; //Local Variables
char x[50],y[50]; // Local Variables
char d;
head=NULL; //Initially head is null
printf("How many books you want to enter?: ");
scanf("%d",&n);
for (i=1; i<=n; i++) // Loop iterate the number of times we have books in quantity.
{
printf("Enter a Book name: ");
fflush(stdin); // To clear buffer memory
gets(x); // Same as scanf
printf("Author: ");
gets(y);
Insert(x,y);
}
Print();
printf("Do you want to sort the data in ascending order?(y/n): ");
scanf("%c",&d);
printf("Your pressed %c",d);
if (d=='y')
{
bsort_print();
}
else
printf("alright!");
return 0;
}
void Insert(char q[50], char r[50]) //Adding items at the end of linked list
{
struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
temp->next=NULL; // Since we are adding a node to the end, we are linking it to NULL.
strcpy(temp->name,q); // copying the contents of "q" to "temp->name"
strcpy(temp->author,r); // same
if(head==NULL)
{
head=temp;
}
else {
struct Node* temp1 = head;
while(temp1->next!=NULL)
temp1=temp1->next;
temp1->next=temp;
}
}
void Print() //Traversing
{
printf("\n");
printf("The Library data is as follows: \n");
struct Node* temp=head;
printf("\n");
while(temp!=NULL)
{
printf("%25s",temp->name);
printf("%25s",temp->author);
temp=temp->next;
printf("\n");
}
}
void bsort_print() //Bubble Sort Algorithm to arrange Library data in Ascending Order
{
int count=1,k=1;
char temp3[50];
struct Node* i=head;
struct Node* j;
struct Node* current=i;
j=i->next;
while(i!=NULL)
{
i=i->next;
count++;
}
for (k=1; k<=count-1; k++)
{
for (count=1; count<count-k; count++)
{
if (strcmp(i->name,j->name)>0)
{
strcpy(temp3,i->name);
strcpy(i->name,j->name);
strcpy(j->name,temp3);
}
j=j->next;
}
}
printf("\n");
printf("The Library data is as follows: \n");
printf("\n");
while(current!=NULL)
{
printf("%25s",current->name);
printf("%25s",current->author);
current=current->next;
printf("\n");
}
}
1 个答案:
答案 0 :(得分：4)
实施气泡排序时遇到的问题
您实现的冒泡排序有一些问题：
-
我认为您的意思是
i <= count-k而不是i<=NULL-k，因为NULL == 0使得语句i<=NULL-k等效于{{1 }}和i<=-k。 -
使用
strcmp而不是i > k，因为您是在比较数组的地址而不是名称。 -
您忘记了在结构中交换作者。
更好的实现方式
在其余代码中需要更改的内容
-
您不必每次都使用数组
i->name>j->name来重复50，#define MAX_STRING_LENGTH 50更具可读性，如果需要更改它，则可以这样做，而不必搜索代码中的所有事件 -
void Insert(char q[50], char r[50]);不需要在函数的参数中指定数组的维数，只需void Insert(char *p, char *r);即可指向char的通用指针。 -
与其将用户输入保存到两个数组中，然后将它们复制到节点中的数组中，不如使用malloc函数将新数组分配给新数组，然后将对它的引用处理到节点中，这样更有效。这样一来，您就不必使用
strcpy（它是O（n）），并且可以降低代码速度。 -
使用
typedef struct node {<ARGS>} Node;定义新的变量类型，以便您可以编写Node*而不是struct Node*来编写代码。
城市复杂度
这是网站lizard.ws对冒泡排序CC的分析结果：
// Imports
//---------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//---------------------------------------------
// Definitions
//---------------------------------------------
#define MAX_STRING_LENGTH 50
//---------------------------------------------
// Type definitions to make the code more readable
//---------------------------------------------
typedef struct node {
char *name;
char *author;
struct node * next;
} Node;
//---------------------------------------------
// Global Variable
//---------------------------------------------
Node* head = NULL;
//---------------------------------------------
// Function protoypes
//---------------------------------------------
void insert(char *q, char *r);
void print_the_list();
void bsort();
//---------------------------------------------
// Main Function :
// Ask the user to insert some books then
// print the list of books
// normally or sorted by book name
//---------------------------------------------
int main() {
head = NULL; //Initially head is null
char *book_name, *book_author;
int n; // Number of book that the user want to enter
printf("How many books you want to enter?: \n");
scanf("%d", &n);
for (int i = 1; i <= n; i++){ // Loop iterate the number of times we have books in quantity.
// To clear buffer memory
fflush(stdin);
// get the name
printf("Enter a Book name: \n");
// allocate the memory for the name of the new book
book_name = (char*) malloc(MAX_STRING_LENGTH*sizeof(char));
gets(book_name); // Same as scanf
// get the author
printf("Author: \n ");
// allocate the memory for the author of the new book
book_author = (char*) malloc(MAX_STRING_LENGTH*sizeof(char));
gets(book_author);
// add it to the list
insert(book_name, book_author);
}
print_the_list();
char d;
printf("Do you want to sort the data in ascending order?(y/n): \n\t");
scanf("%c", & d);
if (d == 'y') {
printf("Soprting the list!");
bsort();
} else
printf("alright!");
print_the_list();
return 0;
}
//---------------------------------------------
// insert(name of the book, authro of the book):
// O(n_of_element_in_the_list)
// append the new book the global list
//---------------------------------------------
void insert(char* name, char* author){ //Adding items at the end of linked list
// create and initialize the new node
Node* new_node = (Node* ) malloc(sizeof(Node));
new_node->author = author;
new_node->name = name;
new_node->next = NULL; // Since we are adding a node to the end, we are linking it to NULL.
// if the list is empty then add the node as the head of the list
if (head == NULL) {
head = new_node;
}
else {
Node * temp = head;
// Traverse the list till the end
while (temp->next != NULL)
temp = temp->next;
// add the new node as the successor of the last node
temp->next = new_node;
}
}
//---------------------------------------------
// print_the_list():
// O(n_of_element_in_the_list)
// print the whole content of the global list
//---------------------------------------------
void print_the_list(){
printf("\nThe Library data is as follows: \n\n");
Node* temp = head;
while (temp != NULL) {
printf("%s\n%s\n\n", temp->name,temp->author);
temp = temp->next;
}
}
//---------------------------------------------
// sort():
// O(n_of_element_in_the_list^2)
// sort the whole list by name in Ascending Order
//---------------------------------------------
void bsort(){ //Bubble Sort Algorithm to arrange Library data in Ascending Order
char *swap_ptr_name, *swap_ptr_author;
// for each node of the list
for (Node* current_minimum = head; current_minimum != NULL; current_minimum = current_minimum->next) {
// for each node after the current_minimum
for (Node* current_node = current_minimum->next; current_node != NULL; current_node = current_node->next) {
// if the current_node is less than the current_minimum swap them
if (strcmp(current_node->name,current_minimum->name) < 0) {
// Save the name and author of the current_minimum
swap_ptr_name = current_minimum->name;
swap_ptr_author = current_minimum->author;
// Place the current node as the minimum
current_minimum->name = current_node->name;
current_minimum->author = current_node->author;
// Place the old minimum in the place of the current_node
current_node->name = swap_ptr_name;
current_node->author = swap_ptr_author;
}
}
}
}
附加说明
代码格式
我建议您阅读一些代码样式指南（GNU，Google），因为在C语言中，如果您不太精确，则代码将变得非常难以阅读。
首先，我认为最好是习惯使用：
编辑
很抱歉，我实现的算法不是冒泡排序。
实际的冒泡排序实现是这样的：
//---------------------------------------------
// sort():
// O(n_of_element_in_the_list^2)
// sort the whole list by name in Ascending Order
//---------------------------------------------
void bsort(){ //Bubble Sort Algorithm to arrange Library data in Ascending Order
// If he list is empty then is already sorted
if(head == NULL)
return;
// Temp pointers to swap two nodes.
char *swap_ptr_name, *swap_ptr_author;
// Variable that keep track if at least one swap was made in the for.
int swapped;
Node* next_node;
do{
// Reset the flag
swapped = 0;
// for each node in the list except the last one
for (Node* current_node = head; current_node->next != NULL; current_node = current_node->next) {
// Set the next node
next_node = current_node->next;
// if the current_node is bigger than the next_node swap them
if (strcmp(current_node->name,next_node->name) > 0) {
// Save the name and author of the current_minimum
swap_ptr_name = next_node->name;
swap_ptr_author = next_node->author;
// Place the current node as the minimum
next_node->name = current_node->name;
next_node->author = current_node->author;
// Place the old minimum in the place of the current_node
current_node->name = swap_ptr_name;
current_node->author = swap_ptr_author;
// We swapped two nodes so the flag is setted
swapped = 1;
}
}
}while(swapped == 1);
}
附加注释2
有一种不用交换ptr就可以交换变量的方法，但是它的可读性较差。 XOR Swap
在这种情况下，它看起来像这样。
// X := X XOR Y
current_node->name ^= next_node->name;
current_node->author ^= next_node->author;
// Y := Y XOR X
next_node->name ^= current_node->name;
next_node->author ^= current_node->author;
// X := X XOR Y
current_node->name ^= next_node->name;
current_node->author ^= next_node->author;
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