Store strings from file into dynamically alocated array - c

Question

I am reading words from a file, exact number 2243. And I am trying to store them inside array so I can read them later on the program. Code is inside function. The file doesn't have sentences, just words one below the other.
char** fill_word_array(char* filename){
int i = 0, j = 0;
int lines = 0;
char str[20];
char *array[i][j];
array[i][j] = malloc(lines * sizeof(char*));
FILE * fp = fopen("words.txt", "r");
if (fp == NULL)
{
printf("Cannot open file");
return 0;
}
while (fscanf(fp, "%s", str) != EOF)
{
lines++;
}
printf("%d\n", lines);
fseek(fp, 0, SEEK_SET);
array[i][j] = malloc(sizeof(char*) * lines);
for(i = 0; i <= lines; i++)
{
strcpy(array[lines][j], str);
printf("%s", array[i][j]);
}
return 0;
}
This code prints only the last word of the file as shown here http://tinypic.com/r/2zhjmgx/9.

Answer 1

A declaration like char *array[i][j] with i==0 and j==0 will reserve an array of size 0, such that even position array[0][0] is not legally accessible (undefined behaviour). So when you write array[i][j] = malloc(lines * sizeof(char*)), you already write to array[0][0] yielding UB.
Usually one gets punished by the community for providing the solution to somebody asking for help and thereby steeling him the chance to make the experiences on his own. For your maturity level, however, it seems to me that the exercise is to hard, and therefore I'll provide a solution following your approach and describe the things that are to consider.
Hope it helps.
With your approach you need to...
count the words
allocate space for "words * sizeof(char*)" +
one word to store a NULL-pointer at the end (otherwise the users
of your result will not know where to stop).
rewind and read in every word in a loop;
in the loop, make a copy of the temporary word content and store it in the array
after the loop, write the
final NULL-pointer.
return the array (and tell the user that he
will have to free memory later)
Here's the code:
char** fill_word_array(char* filename){
int words = 0;
char str[100];
char **array;
FILE * fp = fopen("words.txt", "r");
if (fp == NULL)
{
printf("Cannot open file");
return 0;
}
while (fscanf(fp, "%s", str) != EOF)
{
words++;
}
printf("%d\n", words);
fseek(fp, 0, SEEK_SET);
array = malloc(sizeof(char*) * (words+1));
for(int i = 0; i < words && fscanf(fp, "%s", str) != EOF; i++)
{
array[i] = strdup(str);
}
array[words] = NULL;
return array;
}
int main() {
char **array = fill_word_array("someFile.txt");
for (int i=0; array[i] != NULL; i++) {
printf("%s\n", array[i]);
free(array[i]);
}
free(array);
}