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POCan't find error in string manipulation/pointers
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copied!<p>So first off, this is a homework assignment, so please don't write any code for me, just point out where my code is wrong.</p> <p>The basics of the code is that it's a 'address/balance' book. I've got a struct with my variables, but for some reason, my doubly linked list is getting all messed up and I can't figure out how. With a bit of fancy (not really) debugging, I've figured out that I think the fgets(string, 200, file); line is overwriting my head->name pointer somehow, which seems to throw the rest of the code off. Relevant code snippets here:</p> <p>Populating the List:</p> <pre><code>void populate_list(char* filename){ FILE *file = NULL; char* name = NULL; char* streetaddress = NULL; char* city = NULL; char* state = NULL; char line[200]; int zip; float balance; file = fopen(filename,"r"); if(file==NULL){ printf("Invalid input file\n"); exit(1); } if(file == 0){ printf("Invalid file.\n"); exit(1); } while(!feof(file)){ fgets(line, 200, file); name = strtok(line, ","); streetaddress = strtok(NULL, ","); city = strtok(NULL,","); state = strtok(NULL,","); zip = atoi(strtok(NULL,",")); balance = atof(strtok(NULL,",")); strip_spaces(name); strip_spaces(streetaddress); strip_spaces(city); strip_spaces(state); add_node(name, streetaddress, city, state, zip, balance); } fclose(file); return; } </code></pre> <p>Then the add_node code:</p> <pre><code>void add_node(char* name, char* streetaddress, char* city, char* state, int zip, float, balance){ struct customer* addnode = NULL; if(find_duplicate(name)){ print_filler(1); printf("DUPLICATE RECORD: %s\n", name); return; } else { addnode = (struct customer *) malloc(sizeof(struct customer)); addnode->name = name; addnode->streetaddress = streetaddress; addnode->city = city; addnode->state = state; addnode->zip = zip; addnode->balance = balance; if(head == NULL) { head = addnode; addnode->prev = NULL; } else { tail->next = addnode; addnode->prev = tail; } tail = addnode; addnode->next = NULL; } print_list(); return; } </code></pre> <p>The bug seems to be happening after the first time add_node is called and happens when fgets() goes off a second time. It's overwriting head->name with the entire fgets() line for some reason.</p> <p>There other random irritating bugs I haven't pinned down yet, but this one I think may be the source of the others.</p> <p>Full code is here, if it helps: <a href="http://pastebin.com/k0pqyvT0" rel="nofollow">http://pastebin.com/k0pqyvT0</a></p> <p>My guess is it's something to do with the head->name pointer being overwritten by fgets(), but I can't for the life of me figure out what exactly is doing this, any help/advice would be appreciated.</p> <p>Edit: Solution was to implement strdup() and duplicate the strings when they're passed to add_node(). Thanks for all the answers.</p>

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