Topics (Non-exhaustive) Hash Tables Tries Trees Stacks Queues. HTTP CSS PHP MVC SQL Javascript TCP/IP

Size: px

Start display at page:

Download "Topics (Non-exhaustive) Hash Tables Tries Trees Stacks Queues. HTTP CSS PHP MVC SQL Javascript TCP/IP"

Gilbert Douglas
6 years ago
Views:

1 Topics (Non-exhaustive) Hash Tables Tries Trees Stacks Queues HTTP CSS PHP MVC SQL Javascript TCP/IP

2 Linked Lists head 2 3 9

3 Nodes n next typedef struct node { int n; struct node* next; } node;

4 Search head 2 3 9

5 bool search(node* list, int n) { node* ptr = list; } while (ptr!= NULL) { if (ptr- >n == n) { return true; } ptr = ptr- >next; } return false;

6 Insertion head

7 Insertion head

8 Insertion head

9 Insertion head

10 void insert(int n) { // create new node node* new = malloc(sizeof(node)); // check for NULL if (new == NULL) { exit(1); } // initialize new node new- >n = n; new- >next = NULL; } // insert new node at head new- >next = head; head = new;

11 Doubly Linked Lists head 2 3 9

12 DLL Nodes n next prev typedef struct node { int n; struct node* next; struct node* prev; } node;

13 Hash Tables banana apple kiwi mango Hash Function apple banana cantaloupe kiwi pear cantaloupe mango pear

14 Hash Function banana Hash Function apple cantaloupe kiwi mango pear

15 Hash Function Example int hash_function(char* key) { // hash on first letter of string int hash = toupper(key[0]) - 'A'; } return hash % SIZE;

16 Collisions berry Hash Function apple banana cantaloupe kiwi mango pear

17 Linear Probing berry Hash Function apple banana cantaloupe berry 10 kiwi mango 15 pear

18 Separate Chaining avocado berry cantaloupe apple banana...

19 Tries

20 typedef struct node { // marker for end of word bool is_word; // pointers to other nodes struct node* children[27]; } node;

21 is_word struct node { /* data b */ children z a nodes // pointers to other struct t node* children[26]; }; o o m

22 struct node { /* data b */ z a nodes // pointers to other struct t node* children[26]; }; o o m

23 struct node { /* data b */ z a nodes // pointers to other struct t node* children[26]; }; o o m

24 struct node { /* data b */ z a nodes // pointers to other struct t node* children[26]; }; o o m

25 struct node { /* data b */ z a nodes // pointers to other struct t node* children[26]; }; o o m

26 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

27 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

28 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

29 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

30 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

31 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

32 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

33 struct node { /* data */ b z a nodes // pointers to other struct t node* children[26]; }; o o m

34 struct node { /* data */ b z a // pointers to other nodes struct t node* children[26]; }; h o o m

35 struct node { /* data */ b z a // pointers to other nodes struct t node* children[26]; }; h o o m

36 Tree

37 Root Leaves

38 Binary Tree

39 55 typedef struct node { int n; struct node* left; struct node* right; } node;

40 Binary Search Tree

41 bool search(node* root, int val) { if root is NULL return false. if root- >n is val return true. if val is less than root- >n search left child } if val is greater than root- >n search right child

42 Stacks

43 push pop LIFO

44 typedef struct { char* strings[capacity]; int size; } stack; {

45 push TODOs: size < CAPACITY? store element at [size] size++ [5] [4] [3] [2] [1] [0]

46 [5] pop TODOs: [4] [3] [2] size > 0? size-- return [size] [1] [0]

47 Queues

48 FIFO enqueue dequeue

49 typedef struct { int head; char* strings[capacity]; int size; } queue; {

50 Enqueue TODOs: { size < CAPACITY? store at tail size++ head [5] [4] [3] [2] [1] [0]

51 Dequeue TODOs: { head size > 0? move head size-- return element [5] [4] [3] [2] [1] [0]

52 chmod Unix system call to change file permissions ls - l : see file permissions chmod (each is from 0-7) r : readable : 4 w : writeable : 2 x : executable : 1

54 chmod group+permissions + adds permissions - takes away permissions u: user or owner g: group o: others

55 Example rwx can also be represented as 700 chmod 444 file would give what permissions? What s another way we could write this?

56 Example rwx can also be represented as 700 chmod 444 file would give what permissions? Readable to everyone! Could also do chmod a+r file

57 chmod 555 chmod u+x chmod 640 Translations

58 Translations chmod 555 Chmod a+rx Gives everyone read and execute access chmod u+x Chmod 100 Gives the owner execute access chmod 640 Chmod u+rw, chmod g+r Gives owner read and write permissions Gives group read permission

59 Common cases chmod 711 directory: Use for any directory chmod 644 file.txt: Use for any non-php file you create chmod 600 file.php: Use for PHP files

60 TCP/IP Transmission Control Protocol/Internet Protocol Gives a set of standards that govern how data should be packetized, transmitted, routed and received Increases chances the data will get where you want it to!

61 Ports Need to tell our end destination what type of data is in the packet; packets might be routed in various ways/paths 21: FTP: File transfer protocol 25: SMTP: 53: DNS: Domain Name System What is the IP address of a domain name? 80: HTTP: Webpage 443: HTTPS: Secure webpage

62 HTML & CSS HyperText Markup Language Practice and experiment! Best practices: Close all your tags! Validate your page with W3 Validator Separate markup (HTML) and style (CSS) MVC paradigm to come!

63 CSS Instead of tags, CSS uses selectors Match tags with asributes Selectors can be id : unique #id in a CSS file class: can refer to mulvple blocks.class in a CSS file

64 HTTP HyperText Transfer Protocol

65 HyperText Check out <a href=" really cool website!

66 Transfer Protocol Introduction to the HTTP specification, from

67 An Example Request GET / HTTP/1.1 User- Agent: curl/ Host: <name>: <value> Key: MethodRequest URI Protocol Version field name field value

68 An Example Response HTTP/ OK Server: Apache Content- Type: text/html; charset=utf- 8 Server: Apache Content- Length: Connection: keep- alive Key: Status Code Protocol Version field name field value

69 PHP Think back to pset6 and hello.html!

70 So what is PHP? PHP Hypertext Preprocessor Server side scripvng language Programming language because it has logic (loops, condivon, etc) Can combine with HTML Allows us to create dynamic webpages! Can incorporate HTML and PHP in the same file or pass informavon from separate files

71 Crash Course! Declaring variables No need to specify type! Loosely or dynamically typed -> determined at runtime $var = 3; Arrays can be associative! $array = [key1 => value1, key2 => value2] However, keys are optional! $array = [10, 20, 30] Index would be just like in C! $array[1] = 20;

72 Crash Course! == versus === == checks for equality after type juggling === checks if they are equal and of the same type foreach loop Way to iterate over arrays If there are no keys foreach ($array as $value) { //do this } If there are keys foreach ($array as $key => $value) { //do this }

73 Two ways to pass info GET Information passed via URL POST Passes data in the HTTP message body Consider the data to be hidden compared to GET requests

75 SQL UPDATE Update data in a database table INSERT INTO Insert certain values into a table SELECT Select values to view DELETE Delete from table

76 JavaScript "JavaScript is the best programming language currently in existence. Other people will try to tell you otherwise. They are wrong." Thomas MacWilliam Head Teaching Fellow, 2012

77 index.html: Hello World <!DOCTYPE html> <html> <head> <script type="text/javascript" src="hello.js"> </script> <title>hello, world!</title> </head> <body> Body HTML here </body> </html> hello.js: alert("hello, world!");

78 Hello World

79 Variable Declarations var s = "CS50"; var n = 3.14; var b = true;... alert("type of b: " + typeof(b)); b = "make b a string"; alert("type of b: " + typeof(b));

80 Loops for(/* init */; /* condition*/; /* update */) { /* code */ } while(/* condition */) { /* code */ } do { /* code */ } while(/* condition */);

81 Function Declarations function sum(x, y) { return x + y; } /* or */ var sum = function(x, y) { return x + y; } var sum = sum(3, 5); alert("3 + 5 = " + sum);

82 Arrays in JavaScript var arr = []; var arr2 = ["Arrays", "in", "JS"]; var thirdelement = arr2[2]; var arr2len = arr2.length; var arr3 = [2.3, true, 5]; arr3[2] = "not a number"; arr3[100] = "legit";

83 Objects in JavaScript (1) var emptyobject = {}; emptyobject["newproperty"] = "newvalue"; emptyobject.othernewproperty = "othernewvalue"; alert(emptyobject.othernewproperty); alert(emptyobject["othernewproperty"]);

84 Objects in JavaScript (2) var CS50 = { "course": "CS50", "instructor": "David J. Malan '99", "tfs": ["R.J.", "Ben", "Pat", "Chris"], "psets": 8, "taped": true };

85 Objects in JavaScript (3) var cottage = [ {name: "James", house: "Winthrop"}, {name: "Molly", house: "Cabot"}, {name: "Carl", house: "Kirkland"} ]; for(var i = 0; i < cottage.length; i++) { alert(cottage[i].name); }

86 DOM: Document-Object Model <!DOCTYPE html> <html> <head> <title>hello, world</ title> </head> <body> hello, world </body> </html>

87 DOM: Document-Object Model (2) Examples document.title document.body document.body.innerhtml Useful Functions document.getelementbyid(string) document.getelementsbyclassname(string) document.getelementsbytagname(string)

88 JavaScript Events window.onload = function() { var searchbutton = document.getelementbyid("search_button"); searchbutton.onclick = function() { alert("you clicked the search button"); } } When Document is Ready Find Search Button When Search Button Clicked Alert Message to User

89 MVC Controller Model Database View Presentation Templates Layout Model-View-Controller

90 MVC COMPONENT FUNCTION EXAMPLE Model View Controller - Persistent storage of information - Managing and organizing data - Presentation of information to user - User interface - Handles user requests, gets information from the - MySQL database - Data files - HTML - Minimal PHP (e.g., for iterating over data to print it out) - Min - PHP

91 C$50 Finance: Model

92 C$50 Finance: Controller $result = query("select * FROM some_table"); if ($result!== false) { foreach ($result as &$row) { /* process row of result */ } render("some_template", array("data" => $result)); } else { apologize("error communicating with database."); }

93 some_template.php: C$50 Finance: View <ul> <?php foreach($data as $row):?> <li><?= $row["name"]?></li> <?php endforeach?> </ul>

94 Tips Take practice tests under time constraints Get sleep and rest! Relax Remember to breathe! Put time into your cheat sheet You got this!

95 This was section.

Quiz 1 Review Session. November 17th, 2014

Quiz 1 Review Session. November 17th, 2014 Quiz 1 Review Session November 17th, 2014 Topics (non-exhaustive) pointers linked lists hash tables trees tries stacks queues TCP/IP HTTP HTML CSS PHP MVC SQL HTTP statuses DOM JavaScript jquery Ajax security...