Question

I am getting the following error from valgrind. Conditional jump or move depends on uninitalized values. I have looked around at similar questions but I am not able to find out whats wrong. I have initialized all the variables, but still..

unsigned long hash_word(const char *str)
 {
  unsigned long hash = 5381;
  int c = 0;

  while((c = *str)) // The error occurs here
   {
    hash = ((hash<<5) + hash) + c;
    str++;
   }

 return hash%1999099;
}

The value of str is passed from the main function. I am using leak-check=full and track-origins=yes. Thanks in advance for the help.

First I am initializing a node.

    typedef struct node{
     char word[46];
     struct node *next;
  } node;

The calling code is

  while(!(feof(fp)))
 {
   node *n =  malloc(sizeof(node));
   if (n == NULL)
    {
     return false;
    }
   else
    {
     fscanf(fp,"%s",n->word);

     index = hash_word(n->word);
     .
     .
     .    // further code
   }

Answer 1

This looks like a misunderstanding in what feof() does. It doesn’t return a true value until after a read has failed due to EOF. Therefore, in your last iteration, the fscanf() call fails and thus does not initialize n->word. You should check the return value of fscanf(). If it hits EOF it returns the C value EOF. You could also check for the value 1 indicating a single field was successfully converted.