Re: How to store the contents of a file into a variable

francescomoi@xxxxxxxxxx wrote:

Hi.

I want to store the contents of a file into a variable:
------------
char file_name[] = "/home/user/foo.txt";

You could use:
  const char * file_name = "/home/user/foo.txt"


FILE *my_file;
my_file = fopen(file_name, "r");

I suggest you test "my_file" for NULL.
If it is, there was a problem opening the file.


char *file_data;
fscanf(my_file, file_data);

You have declared a pointer, "file_data", but
not assigned it to point to anything.

You are also missing some {input} format
specifiers.  See your reference book.

Perhaps you need:
  const unsigned int MAX_DATA_SIZE = 256;
  char * file_data;
  file_data = malloc(MAX_DATA_SIZE);
  fscanf(my_file, "%s", file_data);

Or this might work also:
  const unsigned int MAX_DATA_SIZE = 1024;
  char * file_data;
  file_data = malloc(MAX_DATA_SIZE);
  fread(file_data, 1, MAX_DATA_SIZE, my_file);



printf("%s\n", file_name);
printf("%s\n", file_data);
-------------------------

But I get:
------------------------
/home/user/foo.txt
(null)
-------------------------

Of course, my 'foo.txt' file is not empty. Whay am I doing wrong? Thx.


Remember:
1. Always check the return values of:
       malloc
       fopen
       fscanf
       fread

2. The C language does not have a dynamic string
   type.  You will have to know how much to allocate
   at first, then maybe reallocate again.

3. Pointers, when declared, don't point anywhere
   useful.  You will have to make them point to
   something before you use them.

--
Thomas Matthews

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