Linked List (II) CGS 3460, Lecture 37 Apr 12, 2006 Hen-I Yang

Previously… Union and Enum Linked list

Agenda Homework 6 (Finally) Linked List Introduction to preprocessor

Homework 6 2 problems Problem 1: Iterative and Recursive Functions  Convert Decimal Numbers to Binary Representations Problem 2: Linked List  Contact List Homework 6 description Needed.h and.c files.h.c Make sure you check back later today.

Quiz 5 and the Lecture on April 14 Quiz 5 has 3 questions, less questions in each set The material is much harder than any of the previous ones, make sure you spend enough time studying for this Instead of the normal 15 – 20 minutes, I will allot 40 minutes for this quiz and you are allowed to turn in early For the remaining 10 minutes, I will hold a tutorial type Q&A session for any questions related to the materials we’ve covered so far.

Linked List Operations  Start a list  Create a node  Insert  Search  Query  Print

Build a Linked List (I) Build a structure representing a node struct athlete { float speed; struct athlete * next; }; Initialize the node struct athelete *first = NULL;

Build a linked list: Create a node allocate memory for the node storing data into the node; insert the node into the list struct athlete *new_player; new_player = malloc(sizeof(struct athelete)); (*new_player).speed = 9.90; new_player  next = NULL; first = new_player;

Insert a node: insert in the front new_player = malloc(sizeof(struct athelete)); new_player  speed = 9.85; new_player  next = first  next; first = new_player;

Insert a node: insert at the end new_player = malloc(sizeof(struct athelete)); new_player  speed = 10.10; new_player  next = NULL; (first  next)  next = new_player;

Search and Delete Search: for (p = first; p != NULL; p = p  next) { …. } Delete (almost reverse of insertion):  locating the node to be deleted (see search a linked list)  altering the previous node to bypass the deleted node  calling free to reclaim the space occupied by the deleted node What to do to print everything out? (exercise)

Insert a node: insert in between new_player = malloc(sizeof(struct athelete)); new_player  speed = 10.00; new_player  next = NULL; struct athelete * q; for (p = first; p != NULL; p = p  next) { if (p  speed > 10.00) { new_player  next = q  next; q  next = new_player; } q = p; } (first  next)  next = new_player;

Pointer to Functions Pass as an argument in other function Exception handling More flexible (and abstract) programming int (*f) (int);  (a function declaration, not definition) Example:  void qsort(void * base, size_t nmemb, size_t size, int (*compare) (const void *, const void *));

What’s next? Preprocessors  Directives (#include, #define) are handled by preprocessor  Preprocessing is handled prior to compilation C program Modified C prog Object Code  Powerful, but can be hard to debug  Recommended to be used carefully and moderately compilerpreprocessor

Preprocssor Directives Macro definition  #define, #undef File inclusion  #include Conditional Compilation  #if, #ifdef, #ifndef, #elseif, #else Others  #error, #line, #pragma

Q&A It’s your chance to ask the questions.

Summary Linked List Introduction to Preprocessor

Before you go Homework 5 late submission deadline tomorrow at 11:59 pm Make sure you spend enough time study for this quiz on pointers. Pointer is one of the most difficult concepts in C language. Although there are less questions and more time, you will need to understand the concept to do well in this quiz. Ask TA if you have any questions about pointers.