C 如何从文件中获取替代行并将其作为字符串存储到结构中？

我有一个文件需要通过代码读取。该文件如下所示。文件的第一行包含一个整数，表示文件中日记账分录的数量。我需要编写一个C程序来读取文件并将内容存储在动态分配的结构数组中

4
12/04/2010 
Interview went well I think, though was told to wear shoes. 
18/04/2010 
Doc advised me to concentrate on something... I forget. 
03/05/2010
Was asked today if I was an art exhibit. 
19/05/2010 
Apparently mudcakes not made of mud, or angry wasps.

我能够在struct中存储strok（）的日期、月份和年份，但是我一直在将字符串保存到struct中。 这是我的strtok（）代码

程序没有使用strcpy（），当我运行它时，它不断崩溃。但是，如果删除strcpy（），它将按如下方式打印：

12
Interview went well I think, though was told to wear shoes. 
18
Doc advised me to concentrate on something... I forget. 
03
Was asked today if I was an art exhibit. 
19
Apparently mudcakes not made of mud, or angry wasps.

这不是我想要存储在结构中的字符串。我被困在如何将字符串存储到结构中。我的结构是

typedef struct journal{
int day;
int month;
int year;
char entry[1024];
} Diary;

---

任何善良的灵魂都能告诉我哪里不对吗？

以下建议代码：

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

#define MAX_LINE_LEN 1024

struct journal
{
    int day;
    int month;
    int year;
    char entry[ MAX_LINE_LEN ];
};
typedef struct journal Diary;


int main( void )
{

    FILE* file=fopen("struct.txt","r");
    if ( !file )
    {
        perror("fopen failed");}
        exit( EXIT_FAILURE );
    }

    // implied else, fopen successful

    char line[ MAX_LINE_LEN ];
    int size;

    if( fgets( line, sizeof line, file ) )
    {
        if ( sscanf( line, "%d", size ) != 1 )
        {
            fprintf( stderr, "scanf for data count failed\m" );
            exit( EXIT_FAILURE );
        }

        // implied else, input of data count successful
    }

    else
    {
        perror( "fgets for data count failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, fgets successful


    Diary myDiary[ size ];  // uses VLA (variable length array feature of C


    size_t i = 0;
    char *token = NULL;

    while( i < size && fgets( line, sizeof( line ), file) )
    {
        token = strtok( line, "/" );
        if( token )
        {
            myDiary[i].day = atoi( token );

            token = strtok( NULL, "/" );
            if( token )
            {
                myDiary[i].month = atoi( token );

                token = strtok( NULL, "/" );
                if( token )
                {
                    myDiary[i].year = atoi( token );

                    // input data directly into struct instance
                    fgets( myDiary[i].entry, MAX_LINE_LEN, file );
                }
            }
        }
        i++;
    }
}

执行所需的功能

为“神奇”数字提供有意义的名称

将结构定义与该结构的类型定义分开

更新/编辑了最新的问题详细信息

现在建议的守则是：

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

#define MAX_LINE_LEN 1024

struct journal
{
    int day;
    int month;
    int year;
    char entry[ MAX_LINE_LEN ];
};
typedef struct journal Diary;


int main( void )
{

    FILE* file=fopen("struct.txt","r");
    if ( !file )
    {
        perror("fopen failed");}
        exit( EXIT_FAILURE );
    }

    // implied else, fopen successful

    char line[ MAX_LINE_LEN ];
    int size;

    if( fgets( line, sizeof line, file ) )
    {
        if ( sscanf( line, "%d", size ) != 1 )
        {
            fprintf( stderr, "scanf for data count failed\m" );
            exit( EXIT_FAILURE );
        }

        // implied else, input of data count successful
    }

    else
    {
        perror( "fgets for data count failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, fgets successful


    Diary myDiary[ size ];  // uses VLA (variable length array feature of C


    size_t i = 0;
    char *token = NULL;

    while( i < size && fgets( line, sizeof( line ), file) )
    {
        token = strtok( line, "/" );
        if( token )
        {
            myDiary[i].day = atoi( token );

            token = strtok( NULL, "/" );
            if( token )
            {
                myDiary[i].month = atoi( token );

                token = strtok( NULL, "/" );
                if( token )
                {
                    myDiary[i].year = atoi( token );

                    // input data directly into struct instance
                    fgets( myDiary[i].entry, MAX_LINE_LEN, file );
                }
            }
        }
        i++;
    }
}

#包括
#包括
#定义最大线长度1024
结构日志
{
国际日；
整月；
国际年；
字符输入[最大行长度]；
};
typedef结构日志；
内部主（空）
{
FILE*FILE=fopen（“struct.txt”、“r”）；
如果（！文件）
{
perror（“fopen失败”）；}
退出（退出失败）；
}
//否则，fopen成功了
字符行[MAX_line_LEN]；
整数大小；
if（fgets（行、行大小、文件））
{
如果（sscanf（行，“%d”，大小）！=1）
{
fprintf（stderr，“扫描数据计数失败\m”）；
退出（退出失败）；
}
//否则，数据计数输入成功
}
其他的
{
perror（“数据计数的FGET失败”）；
退出（退出失败）；
}
//否则，fgets将获得成功
日记我的日记[大小]；//使用VLA（C的可变长度数组功能
尺寸i=0；
char*token=NULL；
而（i

您的问题提出了一个经典问题：“当我事先不知道有多少时，如何读取和分配某物的X号？”这实际上是一个更简单的问题，因为您可以从数据文件中读取

X

号作为第一行

（在阅读第一行之后，这将问题简化为单个X结构的分配-否则您需要根据需要跟踪当前分配的结构数量和

realloc

）

首先，我建议不要创建

char条目[1024]；

在您的结构中，有两个原因-第一，在堆栈上创建了

条目的自动存储，并且一个大的日志很容易堆栈溢出…第二，这只是浪费。如果目标是动态分配，那么只分配每个
条目所需的存储。您可以声明一个
1024的缓冲区
char用作读取缓冲区，但随后仅分配
strlen（buf）+1
char来保存条目（从条目中修剪包含的
'\n'
后）

问题的其余部分是任何可靠代码的基础，只是验证每次读取、每次解析和每次分配，以确保您处理的是有效数据，并在整个代码中拥有有效存储。这适用于您编写的每一段代码，而不仅仅是此问题

将这些部分放在一起，并在下面的评论中提供进一步的详细信息，您可以执行以下操作：

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

typedef struct journal {
    int day,
        month,
        year;
    char *entry;    /* declare a pointer, allocate only need No. of chars */
} diary_t;

#define MAXLENGTH 1024  /* max read buf for diary entry */

int main (int argc, char **argv) {

    size_t entries = 0, i, n = 0;
    char buf[MAXLENGTH] = "";
    diary_t *diary = NULL;
    FILE *fp = argc > 1 ? fopen (argv[1], "r") : stdin;

    if (!fp) {  /* validate file open for reading */
        fprintf (stderr, "error: file open failed '%s'.\n", argv[1]);
        return 1;
    }

    /* read first line, parse number of entries */
    if (!(fgets (buf, MAXLENGTH, fp)) ||        /* validate read */
        sscanf (buf, "%zu", &entries) != 1) {   /* validate conversion */
        fputs ("error: failed to read 1st line.\n", stderr);
        return 1;
    }

    /* allocate/validate entries number of diary_t */
    if (!(diary = calloc (entries, sizeof *diary))) {
        perror ("calloc-diary_pointers");
        return 1;
    }

    for (i = 0; i < entries; i++) { /* loop No. entries times */

        size_t len = 0;
        if (!fgets (buf, MAXLENGTH, fp)) {  /* read/validate date */
            fprintf (stderr, "error: failed to read date %zu.\n", i);
            return 1;
        }
        if (sscanf (buf, "%d/%d/%d",    /* parse into day, month, year */
                    &diary[i].day, &diary[i].month, &diary[i].year) != 3) {
            fprintf (stderr, "error failed to parse date %zu.\n", i);
            return 1;
        }

        if (!fgets (buf, MAXLENGTH, fp)) {  /* read entry */
            fprintf (stderr, "error: failed to read entry %zu.\n", i);
            return 1;
        }

        len = strlen (buf);                 /* get length */
        if (len && buf[len - 1] == '\n')    /* check last char is '\n' */
            buf[--len] = 0;                 /* overwrite with nul-character */
        else if (len == MAXLENGTH - 1) {    /* check entry too long */
            fprintf (stderr, "error: entry %zu exceeds MAXLENGTH.\n", i);
            return 1;
        }

        /* allocate/validate memory for entry */
        if (!(diary[i].entry = malloc ((len + 1)))) {
            perror ("malloc-diary_entry");
            fprintf (stderr, "error: memory exausted, entry[%zu].\n", i);
            break;  /* out of memory error, don't exit, just break */
        }
        strcpy (diary[i].entry, buf);   /* copy buf to entry */

        n++;    /* increment successful entry read */
    }
    if (fp != stdin) fclose (fp);   /* close file if not stdin */

    for (i = 0; i < n; i++) {   /* output diary entries */
        printf ("entry[%2zu]:  %2d/%2d/%4d - %s\n", i, diary[i].day,
                diary[i].month, diary[i].year, diary[i].entry);
        free (diary[i].entry);  /* don't forget to free entries */
    }
    free (diary);   /* don't forget to free diary */

    return 0;
}

示例使用/输出

$ ./bin/diary <dat/diary.txt
entry[ 0]:  12/ 4/2010 - Interview went well I think, though was told to wear shoes.
entry[ 1]:  18/ 4/2010 - Doc advised me to concentrate on something... I forget.
entry[ 2]:   3/ 5/2010 - Was asked today if I was an art exhibit.
entry[ 3]:  19/ 5/2010 - Apparently mudcakes not made of mud, or angry wasps.

> bin\diary.exe dat\diary.txt
entry[ 0]:  12/ 4/2010 - Interview went well I think, though was told to wear shoes.
entry[ 1]:  18/ 4/2010 - Doc advised me to concentrate on something... I forget.
entry[ 2]:   3/ 5/2010 - Was asked today if I was an art exhibit.
entry[ 3]:  19/ 5/2010 - Apparently mudcakes not made of mud, or angry wasps.

（注意：所有日记条目（整个日记）所需的存储空间仅为
309字节
，小于
1/10
声明
char条目所需的存储空间[1024]；
）

始终确认已释放所有已分配的内存，并且没有内存错误


MS Windows

由于您在windows上似乎遇到了问题，下面是上面的代码，除了用
%lu
代替
%zu
（因为windows将
%zu
视为一个文本）之外，没有其他内容，而是在Win7上使用旧版本的VS编译器编译的：

> cl /?
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.30319.01 for 80x86
Copyright (C) Microsoft Corporation.  All rights reserved.

编译

$ cat dat/diary.txt
4
12/04/2010
Interview went well I think, though was told to wear shoes.
18/04/2010
Doc advised me to concentrate on something... I forget.
03/05/2010
Was asked today if I was an art exhibit.
19/05/2010
Apparently mudcakes not made of mud, or angry wasps.

> cl /nologo /Wall /wd4706 /wd4996 /Ox /Foobj/diary /Febin/diary /Tc diary.c

（注意：我将.obj文件放在子目录
/obj
中，将二进制可执行文件放在
/bin
中，以保持源目录干净。这就是上面
/Foobj/diary
和
/Febin/diary
的目的）

示例使用/输出

$ ./bin/diary <dat/diary.txt
entry[ 0]:  12/ 4/2010 - Interview went well I think, though was told to wear shoes.
entry[ 1]:  18/ 4/2010 - Doc advised me to concentrate on something... I forget.
entry[ 2]:   3/ 5/2010 - Was asked today if I was an art exhibit.
entry[ 3]:  19/ 5/2010 - Apparently mudcakes not made of mud, or angry wasps.

> bin\diary.exe dat\diary.txt
entry[ 0]:  12/ 4/2010 - Interview went well I think, though was told to wear shoes.
entry[ 1]:  18/ 4/2010 - Doc advised me to concentrate on something... I forget.
entry[ 2]:   3/ 5/2010 - Was asked today if I was an art exhibit.
entry[ 3]:  19/ 5/2010 - Apparently mudcakes not made of mud, or angry wasps.

您必须确保将每个
%zu
更改为
%lu
，否则无法获得正确的输出。您说您已将所有更改为
int
，但您在下面的评论中发布的代码段包含
%zu
——这在windows上不起作用

请仔细检查，如果您还有其他问题，请告诉我。
有两个
fgets
呼叫吗？一个用于日期行，一个用于“输入”行。在
h[i]=atoi中
h
是什么；
？请提供一个。如果我这样做，我应该将日期行和输入行存储到哪里？我尝试使用fgets作为日期和输入，然后继续使用另一个