Question

I’ve got a function which is supposed to add a file to a node of a linked list, each file is a structure containing a constant char *name. The function uses parameters of a linked list and a const char[] (which will name of new data struct). Everything goes smoothly until I try to call the function again, the name of my first data gets changed to the new one, I think I am forgetting to allocate memory somewhere. (or I am screwing up with the const chars)

(here’s the section of code which puts const char[] new_name into a spot in the list)

  node->data_list[node->data_count].data_name = new_name;
  node->data_count++;

Answer 1

if data_name is a char* and new_name is a char[] this:

node->data_list[node->data_count].data_name = new_name;

does not copy new_name into data_name but just means that data_name points to new_name. Each data_name in the list will be pointing to new_name.

You need to malloc() and strcpy():

node->data_list[node->data_count].data_name = malloc(strlen(new_name) + 1);
strcpy(node->data_list[node->data_count].data_name, new_name);

Remember to:

free(node->data_list[node->data_count].data_name);

when no longer required.