Strdup() not working

Question

Probably it is very basic and everyone will shout at me, but I've been trying to fix that for hours and can't take it anymore. I have this structure

struct node
{
Key_Type element;
tree_ptr left, right;
};

And I am trying to put a word into element using strdup like that:

newNode->element = strdup(word);

I understand that it's probably not working because I am trying to allocate a pointer to a normal variable, but I don't know how to fix that.

Table insert(Key_Type word,Table root)
{ 
struct node *newNode = malloc(sizeof(struct node));
struct node *left = malloc(sizeof(struct node));
struct node *right = malloc(sizeof(struct node));
newNode = root->head;
//fprintf (stderr, "Hi\n");
while(newNode->element != NULL)
{
    //printf("%s",word);
    if(strcmp(word,newNode->element) == 0)
    {
        fprintf (stderr, "Hi\n");
        return root;
    }
    while(strcmp(word,newNode->element) == -1)
    {
        //fprintf (stderr, "Hi\n");
        newNode = newNode->left;
        //fprintf (stderr, "Hi\n");
    }//if
    //fprintf (stderr, "Hi\n");
    while(strcmp(word,newNode->element) == 1)
    {
            //fprintf (stderr, "Hi\n");
            newNode = newNode->right;
            //fprintf (stderr, "Hi\n");
    }//else if
}
//createNode(word);
newNode->element = strdup(word);
newNode->left = left;
newNode->right = right;
//fprintf (stderr, "Hi\n");
//printf("%s",root->head->element);
   return root;
}

Answer 1

Extending upon @unwind's answer, strdup() is not a standard C function, and is available on POSIX complaint systems only. Chances are you do not have an strdup implemented in your system.

Here is a possible implementation of strdup()

char *strdup(const char *c)
{
    char *dup = malloc(strlen(c) + 1);

    if (dup != NULL)
       strcpy(dup, c);

    return dup;
}