Question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_ENTRY 100

    //define struct
typedef struct StudentRecords
{
    int StudentID; //must be of size 7 between 1000000 and 9999999
    char *Firstname; //= MALLOC(256*sizeof(char)); // must be any length and allocate memory dynamically.
    char *Lastname; //= MALLOC(256*sizeof(char));
    char *Department; //= MALLOC(256*sizeof(char));
    float GPA; // must be between 0 and 4
} STUDENTRECORDS; 

//define linked list structs
struct Node 
{
struct StudentRecords data;
struct Node* next;
struct Node* prev;
};

//define global head
struct Node* head;
struct Node* GetNewNode(struct StudentRecords Record)
{
struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
newNode->data = Record;
newNode->prev = NULL;
newNode->next = NULL;
return newNode;
}

//create a function to use the struct
void Insert(struct StudentRecords Record)
{
struct Node* newNode = GetNewNode(Record);
if (head==NULL) 
{
    head = newNode;
    return;
}

head->prev = newNode;
newNode->next = head;
head= newNode;
}

void Print() {
struct Node* temp = head;
printf("StudentID: ");
while (temp != NULL) 
{
    printf("%d\n", temp->data.StudentID);
    temp = temp->next;
}

}

void ReversePrint()
{   
struct Node* temp = head;
if (temp == NULL) 
{
    return;
}

while (temp->next != NULL)
{
    temp = temp->next;
}

printf("Reverse: ");
while (temp!= NULL) 
{
    printf("%d", temp->data);
    temp = temp->prev;
}
printf("\n");
}

int main()
{
    /*
    First job is read the file
    */

    //set variables
    int i=0;
    char filecontent, file_name[100];
    FILE *fp;

    STUDENTRECORDS StudentRecords[MAX_ENTRY];
    for(i=0;i<MAX_ENTRY;i++)
    {
        StudentRecords[i].Firstname = malloc(sizeof(char)*256);
        StudentRecords[i].Lastname = malloc(sizeof(char)*256);
        StudentRecords[i].Department = malloc(sizeof(char)*256);        
    }

    printf("Enter directory of file\n"); // instructs user to enter directory of file
    gets(file_name); //prompt use

    fp = fopen(file_name,"r"); //opens the file "r" is read mode for fopen()

    // here is a check to see if fp is empty and throw an error if so
    if (fp == NULL)
    {
        perror("Could not open file\n");
        //exit(EXIT_FAILURE);
    }

//this adds the content to the struct we created.
// and prints it
    i=0;
printf("Records in struct:\n");
    while(EOF!=fscanf(fp, "%d %s %s %s %f\n", &StudentRecords[i].StudentID, StudentRecords[i].Firstname, StudentRecords[i].Lastname, StudentRecords[i].Department, &StudentRecords[i].GPA))
    {

        printf("%d %s %s %s %f\n", StudentRecords[i].StudentID, StudentRecords[i].Firstname, StudentRecords[i].Lastname, StudentRecords[i].Department, StudentRecords[i].GPA);
        i++;
    }

printf("Creating linked list of structs...\n");
//Now we have to add it to a linked list.
for (i=0; i < sizeof(StudentRecords)/sizeof(StudentRecords[0]); i++) 
    Insert(StudentRecords[i]);


//Insert(StudentRecords[0]);
//Insert(StudentRecords[1]);

//print function for linked list
printf("Printing linked list...\n");
Print();    

    // fclose() must follow an fopen()
    fclose(fp);

    return 0;
}

这是我正在编写的程序的完整代码。我要输入一个如下所示的文本文件：

2040003 AAAA BBBBBBBBB ComputerScience 3.4

2040002 AAA CCC ElectricalEngineering 3.01

2040005 AAAAAAAAAAAAAAAAA BBB ComputerScience 3.60

输出将按第一个int或StudentID排序，并以逗号分隔

2040002，AAA，CCC，电机工程学，3.01

2040003，AAAA，BBBBBBBBB，ComputerScience，3.45

2040005，AAAAAAAAAAAAAAAAA，BBB，ComputerScience，3.60

我正在考虑在结构进入链表时对结构进行排序，而不是之后。我想我可以改变我的Insert（）函数以正确的顺序放置它们，但我尝试过的一切都没有用。所以这里的代码只需打印列表而无需任何排序。

感谢您提出任何建议或指示。

Answer 1

你的插入功能看起来应该是这样的

void Insert(struct StudentRecords Record)
{
  struct Node* newNode = GetNewNode(Record);
  struct Node *tmp = head;
  /* Check if we need to insert at head */
  if (head==NULL)
  {
    head = newNode;
    return;
  }

  /* Check if new node is smaller than head */
  if (head->data.StudentID > Record.StudentID) {
    head->prev = newNode;
    newNode->next = head;
    head = newNode;
    return;
  }

  /* Find the node previous to node having StudentID > "StudentID in new node" */
  while(tmp->next && tmp->next->data.StudentID < Record.StudentID)
    tmp = tmp->next;

  /* Insert the new node */
  newNode->next = tmp->next;
  if (tmp->next)
    tmp->next->prev = newNode;
  tmp->next = newNode;
  newNode->prev = tmp;
 }

C编程 - 在结构进入链表时对结构进行排序

1 个答案: