c - 使用链接列表将文件中的单词读取到动态字符中

Question

我正在尝试从文件中读取数据并将数据保存到链接列表中。我们无法将 char 字变成静态 char。我们必须使用 char *word 使其动态地接受任意长度的单词。我无法从文件中读取单词并将其保存到动态字符中。我之前用 static char 做过这件事，这很简单。这是代码。

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

struct node {
    char *word;
    struct node *next;
};

struct codex {
    char *word;
    struct codex *next;
};

struct node *loadWords(FILE *stream);

int main() {
    struct node *head;
    FILE *stream;
    head = loadWords(stream);
    return 0;
}

struct node *loadWords(FILE *stream) {
    struct node *poem;
    struct node *temp;
    char *words, *currentWord;
    size_t chrCount;
    stream = fopen("hw8.data", "r");

    rewind(stream);

    while(!feof(stream)) {
        if(temp = (struct node*)calloc(1, sizeof(struct node)) == NULL) {
            printf("ERROR - Could not allocate memory.\n");
            exit(0);
        }
        getline(&words, &chrCount, stream);
        currentWord = strtok(words, " ");
        strcpy(temp->word, words);
        head->next = temp;
        head = head->next;
    }

    return poem;
}

我该如何动态地执行此操作？

Answer 1

这使用 getline 从文件中读取每一行。如果words设置为NULL并且chrCount设置为零，getline将分配存储文件中的行所需的内存。
当该行被标记化时，一个结构被调用。 strdup 将分配内存来存储 token 并将 token 复制到结构中。
新的结构被添加到链表的末尾。为单词分配的内存被释放，并且为下一行重置单词和 chrCount。
只要 getline 返回大于 0 的值，循环就会继续。
在 main 中，遍历列表并打印每个单词，然后再次遍历，释放分配的内存。

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

struct node {
    char * word;
    struct node* next;
};

struct node *loadWords(FILE *stream);

int main()
{
    FILE *stream = NULL;
    struct node *head;
    struct node *temp;
    struct node *loop;
    head = loadWords(stream);
    if ( head == NULL) {
        return 1;
    }
    temp = head;//print each word
    while ( temp != NULL) {
        printf ( "%s\n", temp->word);
        temp = temp->next;
    }

    temp = head;// free memory
    while ( temp != NULL) {
        loop = temp->next;
        free ( temp->word);
        free ( temp);
        temp = loop;
    }
    return 0;
}

struct node *loadWords(FILE *stream) {
    struct node *loop = NULL;
    struct node *temp = NULL;
    struct node *head = NULL;
    char *words = NULL;
    char *currentWord;
    size_t chrCount = 0;
    if ( ( stream = fopen("hw8.data", "r")) == NULL) {
        printf ("could not open file\n");
        return NULL;
    }

    while( getline( &words, &chrCount, stream) > 0) {//read a line from file
        currentWord = strtok(words, " ");//get first token
        while ( currentWord != NULL) {//loop through tokens
            if((temp = calloc(1, sizeof(struct node))) == NULL) {
                printf("ERROR - Could not allocate memory.\n");
                exit(0);
            }
            temp->word = strdup ( currentWord);//allocate memory and copy token to word
            if ( head == NULL) {
                head = temp;//first structure
            }
            else {
                loop = head;
                while ( loop->next != NULL) {//loop to last structure
                    loop = loop->next;//add structure to end
                }
                loop->next = temp;
            }
            currentWord = strtok(NULL, " ");//next token
        }
        free ( words);//release memory
        chrCount = 0;//so readline will allocate memory for next line
        words = NULL;
    }
    fclose ( stream);
    return head;
}