從文件讀取結構到終端，分段錯誤

Question

我想從具有類似行的文本文件中讀取（其中大約200個具有一些空行，然後）。 我知道某些東西可能是未初始化的，但我對它是什麼是空白的。我現在想要做的只是從文件中讀取並打印到終端窗口中。

我真的希望你能幫助我！ 謝謝。的文本文件中的幾行

例子：

Fre  19/07 18.30  AGF - FCM  0 - 2  9.364 
Lor  20/07 17.00  VFF - RFC  2 - 2  4.771 
Son  21/07 14.00  OB - SDR  1 - 1  7.114 

我的結構是這樣的：

struct match { 
    char weekday[MAX_NAME_LEN]; 
    int day; 
    int month; 
    int hours; 
    int minutes; 
    char home_team[MAX_NAME_LEN]; 
    char away_team[MAX_NAME_LEN]; 
    int home_team_goals; 
    int away_team_goals; 
    int spectators_thds; 
    int spectators_hdrs; 
}; 

我read_file功能如下：

void read_file(struct match *match) { 
    FILE *fp; 
    int i; 
    fp = fopen("superliga-2013-2014", "r"); 
    while (!fp) { 
     error("Cannot open file."); 
    } 

    struct match *matches = (struct match *) malloc(sizeof(match) * MAX_MATCHES); 
    while(!feof(fp)) { 
     fscanf(fp, " %s %i/%i %i.%i %s - %s %i - %i %i.%i \n", 
       matches[i].weekday, &matches[i].day, &matches[i].month, &matches[i].hours, 
       &matches[i].minutes, matches[i].home_team, matches[i].away_team, 
       &matches[i].home_team_goals, &matches[i].away_team_goals, 
       &matches[i].spectators_thds, &matches[i].spectators_hdrs); 
    } 
    fclose(fp); 
    free(fp); 
} 

而且我main功能如下所示：

int main(int argc, char *argv[]) { 
    int i; 
    struct match *matches; 
    void read_file(struct match *matches); 
    for (i = 0; i < MAX_MATCHES; ++i) { 
     printf(" %s %i/%i %i.%i %s - %s %i - %i %i.%i ", 
       matches[i].weekday, matches[i].day, matches[i].month, matches[i].hours, 
       matches[i].minutes, matches[i].home_team, matches[i].away_team, 
       matches[i].home_team_goals, matches[i].away_team_goals, 
       matches[i].spectators_thds, matches[i].spectators_hdrs); 
    } 

    return 0; 
} 

它編譯沒有問題，但我試圖運行它時得到一個Segmentation fault。然後我用Valgrind的，它給了我這個消息：

==12799== Use of uninitialised value of size 8 
==12799== at 0x4007B8: main (in /home/dradee/Dropbox/UNI/Programmering/C/readfile) 
==12799== 
==12799== Invalid read of size 4 
==12799== at 0x4007B8: main (in /home/dradee/Dropbox/UNI/Programmering/C/readfile) 
==12799== Address 0x34 is not stack'd, malloc'd or (recently) free'd 
==12799== 
==12799== 
==12799== Process terminating with default action of signal 11 (SIGSEGV) 
==12799== Access not within mapped region at address 0x34 
==12799== at 0x4007B8: main (in /home/dradee/Dropbox/UNI/Programmering/C/readfile) 

Answer 1

1. Don't投malloc()

   struct match *matches = (struct match *) malloc(sizeof(match) * MAX_MATCHES); 
   

   是更好，因爲

   struct match *matches = malloc(sizeof(struct match) * MAX_MATCHES); 
   

2. 檢查的malloc()的結果，返回NULL失敗。

3. 不檢查!feof()，因爲它是always wrong，所以改變這種

   while(!feof(fp)) 
   

   與

   while (fscanf(fp, " %s %i/%i %i.%i %s - %s %i - %i %i.%i \n", 
        matches[i].weekday, &matches[i].day, &matches[i].month, &matches[i].hours, 
        &matches[i].minutes, matches[i].home_team, matches[i].away_team, 
        &matches[i].home_team_goals, &matches[i].away_team_goals, 
        &matches[i].spectators_thds, &matches[i].spectators_hdrs) == 11) 
   

4. 這是最重要：您在printf()循環迭代，直到MAX_MATCHES ，當你不一定已經閱讀MAX_MATCHES。所以你需要保留一個成功讀取項目的計數，並在第二個for循環中使用它。

   例如，您可以將讀取的項目數從read_file返回給main，然後使用它。

   您已在read_file()有一個計數器，但請閱讀下一點。

5. 您永遠不會在循環中增加iread_file()。

6. 這是非常weired

   void read_file(struct match *matches); 
   

   你的意思

   read_file(matches); 
   

7. 這是不正確

   free(fp); 
   

   你已經做了fclose(fp)這是正確的方式來釋放FILE *的資源，free()會導致未定義的行爲，這可能是分段錯誤或其他任何事情，因爲它是未定義的。

8. 這是沒有意義的

   while (!fp) { ... } 
   

   你的意思

   if (!fp) { ... } 
   

9. 你read_file()功能僅localy分配structs，然後你必須從main()他們用不上，你可以做什麼這

   int read_file(struct match **matches) 
   { 
       FILE   *fp; 
       int   i; 
       struct match *match;   
       if (matches == NULL) 
        return 0; 
       *matches = NULL; 
       fp  = fopen("superliga-2013-2014", "r"); 
       if (!fp) 
       { 
        error("Cannot open file."); 
        return 0; 
       }   
       match = malloc(sizeof(struct match) * MAX_MATCHES); 
       if (match == NULL) 
        return 0; 
       while ((fscanf(fp, " %s %i/%i %i.%i %s - %s %i - %i %i.%i \n", 
          match[i].weekday, &match[i].day, &match[i].month, &match[i].hours, 
          &match[i].minutes, match[i].home_team, match[i].away_team, 
          &match[i].home_team_goals, &match[i].away_team_goals, 
          &match[i].spectators_thds, &match[i].spectators_hdrs) == 11) && (i < MAX_MATCHES)) 
       { 
        i++; 
       } 
       fclose(fp); 
   
       *matches = match; 
       return i; 
   } 
   

   然後你main()

   int main(int argc, char *argv[]) 
   { 
       int   i; 
       struct match *matches; 
       int   count; 
       count = read_file(&matches); 
       for (i = 0 ; i < MAX_count ; ++i) 
       { 
        printf(" %s %i/%i %i.%i %s - %s %i - %i %i.%i ", 
          matches[i].weekday, matches[i].day, matches[i].month, matches[i].hours, 
          matches[i].minutes, matches[i].home_team, matches[i].away_team, 
          matches[i].home_team_goals, matches[i].away_team_goals, 
          matches[i].spectators_thds, matches[i].spectators_hdrs); 
       } 
       free(matches);   
       return 0; 
   }