Arrays of strings are useful when we need to read and process text files line by line. This article explains how to use arrays of strings in C and provides a simple working example.

The following example reads a file into an array of strings

#include <stdio.h>
#include <malloc.h>
#include <string.h>
 
#define MAXLINES 256
 
int main ()
{
 
  char **array;		/* Array of strings */
  char line[256];
  int i=0, num=0;
  FILE *fp;
 
 
  array = calloc (MAXLINES, 256);
 
  if ((fp = fopen ("/path/to/file", "rb")) == NULL)
    {
      fprintf (stderr, "unable to open file\n");
      return (1);
    }
 
  while ((fgets (line, 256, fp) != NULL) && (i < MAXLINES))
    {
      array[i] = (char*) malloc(strlen (line) + 1);
      strncpy (array[i], line, 256);
      i++;
    }
 
  num = i;
  array[num] = NULL;
 
  i=0;
 
  while (i<num)
    {
      printf ("Line  %d : %s ", i, array[i]);
      i++;
    }
 
  /* Free the array of strings after use */
  free(array);
 
  return (0);
 
}

Labels: coding, howto