Main Index

1. CSE 331 - Lecture 9 1 Main Index Contents • Chapter 6 • Shifting blocks of elements… • Model of a list object… • Sample list • The list ADT • CLASS list Constructors • CLASS list Operations • CLASS list::iterator Operations • Inserting an element into a list • Removing an element from a list • Ordered lists • Splicing two lists • Summary Slides • NCurses (curses.h) • Background • Curses “Hello World” • Initializing & Shutting down • Moving cursor • I/O (printw, scanw & getch) • Color • Using Special keys (F1, …) • Using the Mouse • Examples • hi.cpp • mvbox.cpp • mvboxM.cpp • tttCM.cpp

2. Curses Library • Allows “text-based” GUI • Curses or Ncurses for Unix/Linux/AIX • PDCurses (Public Domain Curses) for Dos/Windows • Supports mouse, keypads, color, buffered & non-buffered input, and some simple graphics (lines, boxes, etc)

3. Curses (Windows, etc) • Curses works by creating a window / screen / console data structure within which the program moves the cursor and performs output • A refresh() function updates the actual window / screen / console to reflect the logical one • See class web site for URLs of Curses resources / tutotrials / examples/ etc.

4. Curses Basics #include<curses.h> int main() { // always do this first initscr(); // initialize curses // these are optional cbreak(); // input keys immediately available noecho(); // stop echoing inputs nonl(); // faster cursor movement // move cursor to location and output message // upper left screen corner is 0,0 move(12,5); // move cursor to row 12, column 5 printw(“Hello World\n”); // instead of cout << ... refresh(); // make it visible to us getch(); // wait for a key to be hit endwin(); // release window back to shell return 0; }

5. CursesInitialization & Shutdown • Must use • initscr(); // called first to initialize curses • endwin(); // called last to return screen to normal • Probably use • cbreak(); // enable direct keystroke access • noecho(); // prevent echoing of input • nonl(); // speeds cursor movement • getmaxyx(stdscr,h,w); // get screen limits • Notes: • stdscr is the default screen/window

6. CursesMoving cursor & I/O • Cursor & position • move(y,x); // move cursor to line y, char posit x • Upper left of screen is at position 0,0 • getyx(y,x); // returns current cursor location • I/O • printw(“%d %s”, num, str); // cout << • Parameters are same as printf() • Prints in window from current cursor location • scanw(“%f”,&realNum); // cin >> • Parameters are same as scanf() • Reads input stream as directed by format string • getch(); // reads single keystroke • wgetch(stdscr); // reads single keystroke • From indicated window

7. CursesMoving cursor & I/O • Combined movement and I/O • mvprintw(y,x,“%d %s”, num, str); • Prints in window from cursor location y, x • mvscanw(y,x,“%f”,&realNum); • Reads input stream as directed by format string • Making it visible • refresh(); // updates console • Makes it match logical window data structure

8. Curses Color • Only supported on certain terminal types • xterm is good bet • set term=xterm • at unix prompt before running program • start_color(); // initializes color • init_pair(num,fg_color,bg_color); • Creates a COLOR_PAIR of foreground and background colors • xterm has 8 colors and 64 color pairs, max • attron(COLOR_PAIR(num)); • // makes color pair the output attribute until turned off • attroff(COLOR_PAIR(num));

9. Curses COLORS • COLOR_BLACK • COLOR_RED • COLOR_GREEN • COLOR_YELLOW • COLOR_BLUE • COLOR_MAGENTA • COLOR_CYAN • COLOR_WHITE

10. Curses Using Special Keys • To use function keys, arrows, etc. Initialize with • keypad(stdscr,TRUE); • Must be used before both special key input • And before mouse event capture • prevents immediate translation to ASCII • Get key with • int key = getch(); • Test key with keycodes • KEY_DOWN, KEY_UP, KEY_LEFT, KEY_RIGHT • KEY_HOME, KEY_BACKSPACE • KEY_F(n) Function keys, for 0 <= n >= 63 • KEY_DC Delete character • KEY_IC Insert char or enter insert mode • KEY_ENTER Enter or send

11. Curses Mouse Support • Only in Ncurses (Linux & AIX) • Initialize for capture of events with • mousemask(ALL_MOUSE_EVENTS,NULL); • Specific masks (BUTTON1_CLICKED, ...) • Read mouse click with • int key = getch(); or • int key =wgetch(stdscr);

12. Curses Mouse Events • Processing event • Value read will equal KEY_MOUSE • Use getmouse(&event) to recover event from event queue • Use event.bstate to determine button state (which event) • Use event.x and event.y to determine where mouse was clicked in window MEVENT event; // data type for mouse event if (key == KEY_MOUSE) // if it was the mouse if (getmouse(&event) == OK) { // get the event if (event.bstate & BUTTON1_CLICKED) { // so do something with // event.y; and event.x;

13. Example Curses Programs • Source Code is on Class Web Site • Hi • Simple curses “Hello World” program • Mvbox • Moving star shape • Uses keyboard (letter) inputs • mvboxM • Moving star shape • Uses keyboard, special keys, and mouse input • tttCM • TicTacToe • Uses Color, mouse and keyboard inputs

14. Shifting blocks of elements to insert or delete a vector item

15. 15 Main Index Contents Model of a list object with links to next and previous element

16. 16 Main Index Contents The List ADT • The list API documents the member function prototype as well as pre- and postconditions. • provides three constructors to declare a list object.

17. list(); Create an empty list. This is the default constructor. CLASS list <list> Constructors list(int n, const T&value = T()); Create a list with n elements, each having a specified value. If the value argument is omitted, the elements are filled with the default value for type T. Type T must have a default constructor, and the default value of type T is specified by the notation T(). list(T *first, T *last); Initialize the list, using the address range [first, last). 17 Main Index Contents

18. T& back(); Return the value of the item at the rear of the list. Precondition: The vector must contain at least one element. CLASS list <list> Operations bool empty() const; Return true if the vector is empty, false otherwise. T& front(); Return the value of the item at the front of the list. Precondition: The vector must contain at least one element. 18 Main Index Contents

19. void push_back(const T& value); Add a value at the rear of the list. Postcondition: The list has a new element at the rear, and its size increases by 1. CLASS list <list> Operations void pop_back(); Remove the item at the rear of the list. Precondition: The list is not empty. Postcondition: The list has a new element at the rear or is empty. 19 Main Index Contents

20. void push_front(const T& value); Add a value at the front of the list. Postcondition: The list has a new element at the front, and its size increases by 1. CLASS list <list> Operations void pop_front(); Remove the item at the front of the list. Precondition: The list is not empty. Postcondition: The list has a new element at the front or is empty. int size() const; Return the number of elements in the vector. 20 Main Index Contents

21. iterator begin(); Returns an iterator that references the first position (front) of the list. If the list is empty, the iterator value end() is returned. CLASS list <list> Operations const_iterator begin(); Returns a const_iterator that points to the first position (front) of a constant list. If the list is empty, the const_iterator value end() is returned. iterator end(); Returns an iterator that signifies a location immediately out of the range of actual elements. A program must not dereference the value of end() with the * operator. 21 Main Index Contents

22. iterator end(); Returns an iterator that signifies a location immediately out of the range of actual elements. A program must not dereference the value of end() with the * operator. CLASS list <list> Operations const_iterator end(); Returns a const_iterator that signifies a location immediately out of the range of actual elements in a constant list. A program must not dereference the value of end() with the * operator. 22 Main Index Contents

23. void erase(iterator pos); Erase the element pointed to by pos. Precondition: The list is not empty. Postcondition: The list has one fewer element. CLASS list <list> Operations void erase(iterator first, iterator last); Erase all list elements within the iterator range [first, last]. Precondition: The list is not empty. Postcondition: The size of the list decreases by the number of elements in the range. 23 Main Index Contents

24. CLASS list <list> Operations 24 Main Index Contents iterator insert(iterator pos, const T& value); Insert value before pos, and return an iterator pointing to the position of the new value in the list. The operation does not affect any existing iterators. Postcondition: The list has a new element.

25. *: Accesses the value of the item currently pointed to by the iterator. *iter; CLASS list::iterator <list> Operations ++: Moves the iterator to the next item in the list. iter++; --: Moves the iterator to the previous item in the list. iter--; ==: Takes two iterators as operands and returns true when they both point at the same item in the list. iter1 == iter2 !=: Returns true when the two iterators do not point at the same item in the list. iter1 != iter2 25 Main Index Contents

26. Palindromes • Strings that read the same forwards and backwards • Spaces and punctuation are ignored • Approaches (using lists) • 1 – Pop matching pairs of 1st & last chars • 2 – Scan inward to middle, matching corresponding outermost pairs

27. Palindrome (pop matches) // Assume spaces & punctuation removed // by caller; all letters in lower case template<typename T> bool isPal_1(const list<T>& alist) { list<T> copyList; copyList = alist; while (copyList.size() > 0) { if (copyList.front() != copyList.back()) return false; // mismatch, not a palindrome // pop matching pair copyList.pop_front(); copyList.pop_back(); } return true; // all pairs matched & popped }

28. Palindrome (scan inward) // Assume spaces & punctuation removed // by caller; all letters in lower case template<typename T> bool isPal_2(const list<T>& alist) { list<T>::iterator left, right; left = alist.begin(); right = alist.end(); right--; while (left != right) { if (*left != *right) return false; // mismatch, not a palindrome right--; // move right iter 1 posit left if (left == right) return true; // even length string, we’re done left++; // move left 1 posit right } return true; // all pairs matched & popped }

29. SeqSearch // search values [*first,*last)- sequentially template<typename T> List<T>::iterator seqSearch ( list<T>::iterator& first, list<T>::iterator& last, const T& target) { list<T>::iterator iter = first; while((iter != last) && (*iter != target)) iter++; return iter; }

30. 30 Main Index Contents Inserting an element into a list

31. Removing an element from a list

32. 32 Main Index Contents Splicing two lists

33. Ordered Lists • Values maintained in order by key • Numerical • Alphabetical • Lexicographical • Insertion is two step process • Search for first list value (V) equal to or greater than new value • Insertion of new value in front of list value (V) • Examples • Inserting • Removing duplicates • Merging lists

34. Inserting in Ordered List template<typename T> void insertOrder (list<T>& orderedList, const T& item) { list<T>::iterator curr = orderedList.begin(), stop = orderedList.end(); // find insertion spot, 1st value >= item while((curr != stop) && (*curr < item)) curr++; // insert item ahead of *curr orderedList.insert(curr, item); }

35. Removing Duplicates // assume list is ordered. This way we can jump curr // ahead as soon as we find *p != *curr template<typename T> void removeDups (list<T>& orderedList) { list<T>::iterator curr, p; curr = orderedList.begin(); while (curr != orderedList.end()) { p = curr; p++; while ((p != orderedList.end() && (*p == *curr)) // pass p, move p forward, and call erase orderedList.erase(p++); curr = p; } }

36. 36 Main Index Contents Summary Slide 1 §- list - A Sequence of elements stored by position. - Index access is not available… §- to access the value of an element, must pass through its preceding elements. §-list iterator - A generalized pointer that moves through a list element by element… forward or backward - At any point, the * operator accesses the value of a list item.

37. 37 Main Index Contents Summary Slide 2 §- The list class has two iterator types: 1) iterator: A generalized list traversal pointer. 2) const_iterator: must be used with a constant list object. Each type is a nested class of list and must be accessed by using the scope operator ::

38. 38 Main Index Contents Summary Slide 3 §- the list member function begin() - Gives an iterator an initial value that points to the first element. §- the list member function end() - Returns an iterator pointing just past the last element of the list.

39. 39 Main Index Contents Summary Slide 4 §- The sequential search of a list object - implemented by using an iterator range [first, last). - It returns an iterator that points at the target value or has value last if the target is not in the list.

40. 40 Main Index Contents Summary Slide 5 • §- list class member fns insert() and erase() • - Both use an iterator argument to modify a list. • insert(pos): places value in the list before the data referenced by the iterator pos. • erase(pos): removes the data item referenced by pos from the list.