Inserting word from a text file into a tree in C - c

Question

I have been encountering a weird problem for the past 2 days and I can't get to solve it yet. I am trying to get words from 2 texts files and add those words to a tree. The methods I choose to get the words are refereed here:
Splitting a text file into words in C.
The function that I use to insert words into a tree is the following:
void InsertWord(typosWords Words, char * w)
{
int error ;
DataType x ;
x.word = w ;
printf(" Trying to insert word : %s \n",x.word );
Tree_Insert(&(Words->WordsRoot),x, &error) ;
if (error)
{
printf("Error Occured \n");
}
}
As mentioned in the link posted , when I am trying to import the words from a text file into the tree , I am getting "Error Occured". For once again the function:
the text file :
a
aaah
aaahh
char this_word[15];
while (fscanf(wordlist, "%14s", this_word) == 1)
{
printf("Latest word that was read: '%s'\n", this_word);
InsertWord(W,this_word);
}
But when I am inserting the exact same words with the following way , it works just fine.
for (i = 0 ; i <=2 ; i++)
{
if (i==0)
InsertWord(W,"a");
if (i==1)
InsertWord(W,"aaah");
if (i==2)
InsertWord(W,"aaahh");
}
That proves the tree's functions works fine , but I can't understand what's happening then.I am debugging for straight 2 days and still can't figure it. Any ideas ?

Answer 1

When you read the words using
char this_word[15];
while (fscanf(wordlist, "%14s", this_word) == 1)
{
printf("Latest word that was read: '%s'\n", this_word);
InsertWord(W,this_word);
}
you are always reusing the same memory buffer for the strings. This means when you do
x.word = w ;
you are ALWAYS storing the SAME address. And every read redefine ALL already stored words, basically corrupting the data structure.
Try changing the char this_word[15]; to char *this_word; and placing a this_word = malloc(15);in the beggining of thewhile` loop instead, making it allocate a new buffer for each iteration. So looking like
char *this_word;
while (fscanf(wordlist, "%14s", this_word) == 1)
{
this_word = malloc(15);
printf("Latest word that was read: '%s'\n", this_word);
InsertWord(W,this_word);
}
As suggested by Michael Walz a strdup(3) also solves the immediate problem.
Of course you will also have do free up the .word elements when finished with the tree.

Answer 2

Seems like the problem was in the assignment of the strings.Strdup seemed to solve the problem !