功能分配，主功能不可用

问题描述

我正在尝试为main中的char数组指针数组分配空间并将文件数据放入函数中.运行程序时出现分段错误.谁能告诉我为什么?

I am trying to allocate space and put in file data in my function for my array of char arrays pointer in main. I get a segmentation fault when I run the program. Can anyone tell me why?

datawords [0]在该函数中正确打印.

datawords[0] is printed correctly in the function.

这是我的功能:

void database_extract (char **data_words) {
FILE *f_data;
f_data = fopen("database.txt","r");
struct stat st;
stat("database.txt", &st);
data_words = (char **)malloc(st.st_size * sizeof(char));
if (data_words == NULL) {
  printf("No room\n");
  exit(EXIT_FAILURE);
}
data_words[0] = "test";
printf("%s",data_words[0]);
}

这是我的主旨

int main () {
char **data_words;
database_extract (data_words);
printf("%s",data_words[0]);
}

任何帮助将不胜感激.

推荐答案

您需要向该函数传递一个指向data_words数组的指针，以便在主体中使用分配.

You need to pass to the function a pointer to the data_words array in order to use the allocation in the main.

尝试一下:

void database_extract (char ***data_words) {
FILE *f_data;
f_data = fopen("database.txt","r");
struct stat st;
stat("database.txt", &st);
*data_words = (char **)malloc(st.st_size * sizeof(char));
if (data_words == NULL) {
    printf("No room\n");
    exit(EXIT_FAILURE);
}
data_words[0] = "test";
printf("%s",data_words[0]);

}

和主要内容:

int main () {
char **data_words;
database_extract (&data_words);
printf("%s",data_words[0]);

}

我不确定是否所有*都正确，有时会令我感到困惑，但想法是将指针传递给该函数.

I am not sure if I got all the * right it gets me confused sometimes but the idea is to pass a pointer to the function.

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