C 逐行散列文本文件

我正在尝试散列一个包含19行学生个人信息的文本文件。有一个基于案例的系统，我可以选择要执行的操作，如插入哈希、显示等。代码根本不会读取我提供的文本文件，当我按Display作为操作时，它不会显示任何内容。当我按下Insert选项时，同样的事情也会发生

代码根本无法读取我提供的文本文件

您的问题可能来自：

因为

（line[len-1]！='\n'）

这可能永远不会是真的，因为fgets能够读取一个大的行，并且在这些行只包含很少的数据之后考虑fscanf

为什么要在/*不完整的行*/上工作

在测试的完整线路上工作

if (len && (line[len - 1] == '\n')) 

你也有一个意外的回报

因此，您不能阅读多个答案，请在

else{…}

请注意，您的代码假设用户只请求一次插入，如果他多次请求，您将多次添加相同的元素

在你读了一行之后，你又在文件中读了一遍

因此，您只保存了一半行中的数据，您希望这样做

sscanf(line,"%s %s %s %d",node.AM, node.first_name, node.last_name, &node.grade);

---

你还有其他问题

在散列中，假设标识符至少有7个字符，如果不是这种情况，则使用未定义的行为读取名称（在空字符之后）

做一些类似于：

int Hash(char *AM, int n)
{    
  int i;
  int hashIndex = 0;

  for (i=0; (i< 8) && (AM[i] != 0); i++)
  {
    hashIndex += AM[i];
  }

  return hashIndex % n;
}

您对int但

节点使用格式%d。grade

是一个浮点，用%f替换%d，并检查fscanf返回4

我还鼓励您限制读取字符串的大小，以免冒着从字段中写入的风险，因此（事实上，fscanf必须由sscanf替换）

在

及

您使用格式%d表示int，但给出了

char*

将d替换为s或更改AM的类型（当然还有如何在其他地方读取和使用）

insertToHash末尾的返回是无用的，其他地方还有一些无用的返回

在

及

您使用格式%d表示整数，但给出了双精度

用%lf或%lg等替换%d

在

AM未初始化，行为未定义

你想要

int hashIndex = Hash(node.AM, 19);

在

AM

和

名字

和

姓氏

和

等级

未初始化，行为未定义

你想要

struct node *newnode = createNode(node.AM, node.first_name, node.last_name, node.grade);

并删除无用的变量hashIndex、grade、last\u name、first\u name、AM

在deleteFromHash和searchInHash中执行测试

if (len && (line[len - 1] == '\n')) 

是错误的，因为你比较指针，你想要

if (!strcmp(myNode->AM, AM))

---

在

结构和全局变量使用相同的名称，这不是一个好主意

此外，全局变量节点仅在insertToHash中使用，因此您不需要它，请删除全局变量并将局部变量添加到insertToHash中

---

编辑后，添加主菜单

必须是（2次）

您的变量

first\u name、last\u name

和

grade

未使用

---

考虑到我所有的意见，守则是：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

struct hash *hashTable = NULL;
int eleCount = 0;

struct Node 
{
  float grade;
  char AM[100];
  char first_name[100];
  char last_name[100];
  struct Node *next;
};

struct hash 
{
struct Node *head;
int count;
};

struct Node * createNode(char *AM, char *first_name, char *last_name, float grade) 
{
  struct Node *newNode;

  newNode = (struct Node *) malloc(sizeof(struct Node));
  strcpy(newNode->AM, AM);
  strcpy(newNode->last_name, last_name);
  strcpy(newNode->first_name, first_name);
  newNode->grade = grade;
  newNode->next = NULL;
  return newNode;
}

int Hash(char *AM, int n)
{    
  int i;
  int hashIndex = 0;

  for (i=0; (i< 8) && (AM[i] != 0); i++)
  {
    hashIndex += AM[i];
  }

  return hashIndex % n;
}

void insertToHash() 
{
  struct Node node;

  FILE *fp;
  fp = fopen ("Foitites-Vathmologio-DS.txt","rb");

  if (fp == NULL) 
  { 
    fprintf(stderr,"Could not open file");  
    return;
  } 

  char line[4096];

  while (fgets(line, sizeof line,fp)) {
    size_t len = strlen(line);
    if (len && (line[len - 1] == '\n')) {
      /* complete line */
      if (sscanf(line,"%99s %99s %99s %f",node.AM, node.first_name, node.last_name, &node.grade) != 4) {
    puts("invalid file");
    return;
      }

      int hashIndex = Hash(node.AM, 19);

      struct Node *newNode = createNode(node.AM, node.first_name, node.last_name, node.grade);
      /* head of list for the bucket with index "hashIndex" */

      if (!hashTable[hashIndex].head) 
      {
        hashTable[hashIndex].head = newNode;
        hashTable[hashIndex].count = 1;
      }
      else {
        /* adding new Node to the list */
        newNode->next = (hashTable[hashIndex].head);
        /*
           * update the head of the list and no of
           * Nodes in the current bucket
        */
        hashTable[hashIndex].head = newNode;
        hashTable[hashIndex].count++;
      }
    }
  }
  fclose(fp);
  printf("Done! \n");
}

void deleteFromHash(char *AM) 
{
  /* find the bucket using hash index */
  int hashIndex = Hash(AM, 19);
  int flag = 0;

  struct Node *temp, *myNode;
  /* get the list head from current bucket */

  myNode = hashTable[hashIndex].head;

  if (!myNode) {
    printf("Given data is not present in hash Table!!\n");

    return;
  }

  temp = myNode;
  while (myNode != NULL) {
    /* delete the Node with given AM */
    if (!strcmp(myNode->AM, AM)) {
      flag = 1;
      if (myNode == hashTable[hashIndex].head)
        hashTable[hashIndex].head = myNode->next;
      else
        temp->next = myNode->next;

      hashTable[hashIndex].count--;
      free(myNode);
      break;
    }

    temp = myNode;
    myNode = myNode->next;
  }
  if (flag)
    printf("Data deleted successfully from Hash Table\n");
  else
    printf("Given data is not present in hash Table!!!!\n");
}

void searchInHash(char *AM) {
  int hashIndex = Hash(AM, 19);
  int flag = 0;
  struct Node *myNode;        myNode = hashTable[hashIndex].head;
  if (!myNode) {
    printf("Search element unavailable in hash table\n");
    return;
  }
  while (myNode != NULL) {
    if (!strcmp(myNode->AM, AM)) {
      printf("Student ID  : %s\n", myNode->AM);
      printf("First Name     : %s\n", myNode->first_name);
      printf("Last Name     : %s\n", myNode->last_name);
      printf("grade      : %lg\n", myNode->grade);
      flag = 1;
      break;
    }
    myNode = myNode->next;
  }
  if (!flag)
    printf("Search element unavailable in hash table\n");
}

void display() {
  struct Node *myNode;
  int i;
  for (i = 0; i < eleCount; i++) {
    if (hashTable[i].count == 0)
      continue;
    myNode = hashTable[i].head;
    if (!myNode)
      continue;
    printf("\nData at index %d in Hash Table:\n", i);
    printf("Student ID    First Name    Last Name      Grade   \n");
    printf("--------------------------------\n");
    while (myNode != NULL) {
      printf("%-12s", myNode->AM);
      printf("%-15s", myNode->first_name);
      printf("%-15s", myNode->last_name);
      printf("%lg\n", myNode->grade);
      myNode = myNode->next;
    }
  }
}

int main() 
{
  int n=19, ch;
  char AM[100];
  int insertDone = 0;

  eleCount = n;
  /* create hash table with "n" no of buckets */
  hashTable = (struct hash *) calloc(n, sizeof(struct hash));
  while (1) {
    printf("\n1. Insertion\t2. Deletion\n");
    printf("3. Searching\t4. Display\n5. Exit\n");
    printf("Enter your choice:");
    scanf("%d", &ch);


    switch (ch) {
    case 1: 
      if (insertDone)
        puts("Inserton was already done");
      else {
    /*inserting new Node to hash table */
        insertToHash();
        insertDone = 1;
      }
      break;

    case 2: 
      printf("Enter the AM to perform deletion:");
      scanf("%99s", AM);
      /* delete Node with "AM" from hash table */
      deleteFromHash(AM);
      break;

    case 3: 
      printf("Enter the AM to search:");
      scanf("%99s", AM);
      searchInHash(AM);
      break;
    case 4: 
      display();
      break;
    case 5: 
      exit(0);
    default: 
      printf("U have entered wrong option!!\n");
      break;
    }
  }
  return 0;
}

---

您正在对未初始化的指针调用

inthashindex=Hash（AM，19）

您是否打算调用

inthashindex=Hash（node.AM，19）

？@kiran Biradar我根据这篇文章编写了我的代码，因此我认为这可以回答您的问题，请阅读。最好提供一个简短、完整、可编译的示例，说明您遇到的具体问题。在这种情况下，您提供了太多格式不好的代码（自那以后一直在编辑），但它不包含

intmain（void）

或

intmain（intargc，char*argv[]）

函数，因此它不会编译。请编辑您的帖子，包括您是如何编写主函数的。对于我来说，

（第[len-1]行！='\n'）

必须是

（第[len-1]='\n'）

，您还有几个其他问题，请参阅我的回答。我想我们在这方面取得了一些进展！在我更改主功能之前，特别是在scaf（“%d”、&AM）中，当我选择显示框时，它将仅显示我文件的第一行，但在您建议的更改之后，我将返回ld1 exitstatus@vaskar我将继续更正您的代码，当前显示器将生成我在文件中输入的条目，我已在mu代码中编辑了这些条目，以及您提供给allong的内容和形式的更正我的.txt文件，现在，当我选择“显示”时，它会同时显示两个或三个学生，就像他们在同一个位置一样node@vaskar我将继续编辑我的答案以更正您的代码，请等待我完成，我将警告您，并将完整更正的代码加上一个，以供您的广泛努力。

printf("Student ID  : %d\n", myNode->AM);

printf("%-12d", myNode->AM);

printf("grade      : %d\n", myNode->grade);

printf("%d\n", myNode->grade);

int hashIndex = Hash(AM, 19);

int hashIndex = Hash(node.AM, 19);

struct node *newnode = createNode(AM, first_name, last_name, grade);

struct node *newnode = createNode(node.AM, node.first_name, node.last_name, node.grade);

 if (myNode->AM == AM)

if (!strcmp(myNode->AM, AM))

struct node 
{
  float grade;
  char AM[100];
  char first_name[100];
  char last_name[100];
  struct node *next;
}node;

scanf("%d", &AM);

scanf("%99s", AM);

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

struct hash *hashTable = NULL;
int eleCount = 0;

struct Node 
{
  float grade;
  char AM[100];
  char first_name[100];
  char last_name[100];
  struct Node *next;
};

struct hash 
{
struct Node *head;
int count;
};

struct Node * createNode(char *AM, char *first_name, char *last_name, float grade) 
{
  struct Node *newNode;

  newNode = (struct Node *) malloc(sizeof(struct Node));
  strcpy(newNode->AM, AM);
  strcpy(newNode->last_name, last_name);
  strcpy(newNode->first_name, first_name);
  newNode->grade = grade;
  newNode->next = NULL;
  return newNode;
}

int Hash(char *AM, int n)
{    
  int i;
  int hashIndex = 0;

  for (i=0; (i< 8) && (AM[i] != 0); i++)
  {
    hashIndex += AM[i];
  }

  return hashIndex % n;
}

void insertToHash() 
{
  struct Node node;

  FILE *fp;
  fp = fopen ("Foitites-Vathmologio-DS.txt","rb");

  if (fp == NULL) 
  { 
    fprintf(stderr,"Could not open file");  
    return;
  } 

  char line[4096];

  while (fgets(line, sizeof line,fp)) {
    size_t len = strlen(line);
    if (len && (line[len - 1] == '\n')) {
      /* complete line */
      if (sscanf(line,"%99s %99s %99s %f",node.AM, node.first_name, node.last_name, &node.grade) != 4) {
    puts("invalid file");
    return;
      }

      int hashIndex = Hash(node.AM, 19);

      struct Node *newNode = createNode(node.AM, node.first_name, node.last_name, node.grade);
      /* head of list for the bucket with index "hashIndex" */

      if (!hashTable[hashIndex].head) 
      {
        hashTable[hashIndex].head = newNode;
        hashTable[hashIndex].count = 1;
      }
      else {
        /* adding new Node to the list */
        newNode->next = (hashTable[hashIndex].head);
        /*
           * update the head of the list and no of
           * Nodes in the current bucket
        */
        hashTable[hashIndex].head = newNode;
        hashTable[hashIndex].count++;
      }
    }
  }
  fclose(fp);
  printf("Done! \n");
}

void deleteFromHash(char *AM) 
{
  /* find the bucket using hash index */
  int hashIndex = Hash(AM, 19);
  int flag = 0;

  struct Node *temp, *myNode;
  /* get the list head from current bucket */

  myNode = hashTable[hashIndex].head;

  if (!myNode) {
    printf("Given data is not present in hash Table!!\n");

    return;
  }

  temp = myNode;
  while (myNode != NULL) {
    /* delete the Node with given AM */
    if (!strcmp(myNode->AM, AM)) {
      flag = 1;
      if (myNode == hashTable[hashIndex].head)
        hashTable[hashIndex].head = myNode->next;
      else
        temp->next = myNode->next;

      hashTable[hashIndex].count--;
      free(myNode);
      break;
    }

    temp = myNode;
    myNode = myNode->next;
  }
  if (flag)
    printf("Data deleted successfully from Hash Table\n");
  else
    printf("Given data is not present in hash Table!!!!\n");
}

void searchInHash(char *AM) {
  int hashIndex = Hash(AM, 19);
  int flag = 0;
  struct Node *myNode;        myNode = hashTable[hashIndex].head;
  if (!myNode) {
    printf("Search element unavailable in hash table\n");
    return;
  }
  while (myNode != NULL) {
    if (!strcmp(myNode->AM, AM)) {
      printf("Student ID  : %s\n", myNode->AM);
      printf("First Name     : %s\n", myNode->first_name);
      printf("Last Name     : %s\n", myNode->last_name);
      printf("grade      : %lg\n", myNode->grade);
      flag = 1;
      break;
    }
    myNode = myNode->next;
  }
  if (!flag)
    printf("Search element unavailable in hash table\n");
}

void display() {
  struct Node *myNode;
  int i;
  for (i = 0; i < eleCount; i++) {
    if (hashTable[i].count == 0)
      continue;
    myNode = hashTable[i].head;
    if (!myNode)
      continue;
    printf("\nData at index %d in Hash Table:\n", i);
    printf("Student ID    First Name    Last Name      Grade   \n");
    printf("--------------------------------\n");
    while (myNode != NULL) {
      printf("%-12s", myNode->AM);
      printf("%-15s", myNode->first_name);
      printf("%-15s", myNode->last_name);
      printf("%lg\n", myNode->grade);
      myNode = myNode->next;
    }
  }
}

int main() 
{
  int n=19, ch;
  char AM[100];
  int insertDone = 0;

  eleCount = n;
  /* create hash table with "n" no of buckets */
  hashTable = (struct hash *) calloc(n, sizeof(struct hash));
  while (1) {
    printf("\n1. Insertion\t2. Deletion\n");
    printf("3. Searching\t4. Display\n5. Exit\n");
    printf("Enter your choice:");
    scanf("%d", &ch);


    switch (ch) {
    case 1: 
      if (insertDone)
        puts("Inserton was already done");
      else {
    /*inserting new Node to hash table */
        insertToHash();
        insertDone = 1;
      }
      break;

    case 2: 
      printf("Enter the AM to perform deletion:");
      scanf("%99s", AM);
      /* delete Node with "AM" from hash table */
      deleteFromHash(AM);
      break;

    case 3: 
      printf("Enter the AM to search:");
      scanf("%99s", AM);
      searchInHash(AM);
      break;
    case 4: 
      display();
      break;
    case 5: 
      exit(0);
    default: 
      printf("U have entered wrong option!!\n");
      break;
    }
  }
  return 0;
}

pi@raspberrypi:/tmp $ gcc -g -pedantic -Wextra -Wall c.c
pi@raspberrypi:/tmp $ cat Foitites-Vathmologio-DS.txt
123 aze qsd 1.23
456 iop jkl 4.56
pi@raspberrypi:/tmp $ ./a.out

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:4

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:1
Done! 

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:4

Data at index 7 in Hash Table:
Student ID    First Name    Last Name      Grade   
--------------------------------
456         iop            jkl            4.56

Data at index 17 in Hash Table:
Student ID    First Name    Last Name      Grade   
--------------------------------
123         aze            qsd            1.23

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:1
Inserton was already done

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:3
Enter the AM to search:123
Student ID  : 123
First Name     : aze
Last Name     : qsd
grade      : 1.23

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:3
Enter the AM to search:1234
Search element unavailable in hash table

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:2
Enter the AM to perform deletion:1
Given data is not present in hash Table!!

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:2
Enter the AM to perform deletion:123
Data deleted successfully from Hash Table

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:4

Data at index 7 in Hash Table:
Student ID    First Name    Last Name      Grade   
--------------------------------
456         iop            jkl            4.56

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:2
Enter the AM to perform deletion:456
Data deleted successfully from Hash Table

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:4

1. Insertion    2. Deletion
3. Searching    4. Display
5. Exit
Enter your choice:5
pi@raspberrypi:/tmp $