Thread: reading files into arrays

Originally posted by The Dog
You'll need to get the file size. Once you have it, then you can create a dynamic array with the capacity of the file size in bytes, then fread() the file into an array.

So you wouldn't just use fgets() then?

In that FAQ example, stdin is a FILE* to the default input stream (normally the keyboard), but you can use a stream you've fopen'ed yourself.

@SMB3Master: Do you want to complete file in memory at once? If you, do you understand how to process it once you have it? I'm kinda guessing you just want to read line by line?

@The Dog: You forgot to mention that using fseek/ftell for determining a file size is not suitable to files opened in text mode.
http://www.eskimo.com/~scs/C-faq/q19.12.html

>can you give an example please?

If you choose a fixed-size array with fread (not doing the line-by-line with fgets or using dynamic allocation) you might try something like this.

Code:

#include <stdio.h> 
#include <ctype.h> 

int main(void) 
{
   char text[8];
   size_t i, count = 0;
   FILE *file = fopen(__FILE__, "rb");
   if ( file != NULL )
   {
      count = fread(text, 1, sizeof text, file);
      fclose(file);
   }
   for ( i = 0; i < count; ++i )
   {
      printf("text[%lu]", (long unsigned)i);
      printf(isprint(text[i]) ? " = '%c'\n" : " = 0x%02X\n", text[i]);
   }
   return(0); 
}

/* my output
text[0] = '#'
text[1] = 'i'
text[2] = 'n'
text[3] = 'c'
text[4] = 'l'
text[5] = 'u'
text[6] = 'd'
text[7] = 'e'
*/

Originally posted by SMB3Master
i want to get the file's contents into an array like i said in my first post.

Your question is still ambiguous, imo.

Code:

#include <stdio.h>

int main(void)
{
  FILE *fp;
  char text[6];
  fp = fopen("myfile.txt", "r");
  if (fp)
  {
    if (fgets(text, sizeof(text), fp))
    {
      puts(text);
    }
    
  }
  return(0);
}

If you know what's in the file already, what's the point in reading it in the first place? This program produces the same output (near enough) as the previous one:

Code:

#include <stdio.h>

int main(void)
{
  puts("hello");
  return(0);
}

>>how do i read a text file's content into an array?<<
>>the file contains the word "hello"<<
....
>>the purpose is reading a config file<<

Config files consist of more than the word "hello", I'm sure. The Dogs and Daves answers probably won't help you, they were unfortunatley mislead by your rather vague question. Be more specific next time, and you'll be more likely to get a correct answer.