Mdst 3559-02-17-php2
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Mdst 3559-02-17-php2 Presentation Transcript

  • 1. PHP 2
    MDST 3559: DataestheticsProf. Alvarado02/17/2011
  • 2. Business
    VPN?
  • 3. Review
    PHP
    Variables, Data Types, Functions
    See Chapters 2 through 5 of Programming PHP
    Text
    Earlier we saw the text handled as a tree (CSS, jQuery)
    Tuesday we treated the text as an array, a simple linear sequence,
  • 4. Overview
    Today we will go back over the basics of PHP
    To provide a slightly different angle on the subject
    To help clarify some concepts for those new to programming
    To help clarify the “PHP way” for those with experience
    Then we will cover two new topics
    Regular Expressions
    Creating your own functions
  • 5. PHP as a language
    PHP is a programming langague (of course), but it has analogies to natural language as well
    There are parallels to the basic structures of human languages
    Which makes sense:
    Programming languages are designed to mediate between human and machine language
  • 6. What are some elements of natural language?
  • 7.
  • 8. Some Elements of Natural Language
    Words
    Meanings
    Sentences
    Something is said of something else
    Parts of speech: nouns, verbs, prepositions
    Heart of language as language, beyond mere signs
    Paragraphs
  • 9. PHP has all of these things
  • 10. Values are Meanings
    Values are pieces of data
    Languages are all about doing things with data
    Data comes in types
    Types include strings and numbers
    Also Boolean values (true/false)
    Values are expressed literally and signified like so:
    “Hello, World!”
    5
    true
    These are the meanings of the language
  • 11. Variables are Nouns
    Variables are words that can have meaning
    $POTUS = “Obama”;
    The President of the U.S. is Obama.
    Like the difference between person and office
    They are like nouns that refer to things
    Things being values ...
    They are always prefixed by $ and are case sensitive
  • 12. (Arrays)
    Arrays are admittedly weird
    But they can be thought of as words that stand for collections, e.g.
    The Pittsburgh Steelers
    The UVA student body
    These phrases imply a structure
    Albeit much more complicated than arrays
    But not much: consider rosters ...
  • 13. Functions are Verbs
    Functions are like verbs
    $food = food_shop($me,$money,$humger_level)
    Like verbs, they may require arguments and imply a result
    Verbs are action words
    Consider transitive versus intransitive
    They are not prefixed by $
    They are not case sensitive
    They are followed by parentheses
  • 14. Functions
    Verbs have implicit arguments and effects
    Subjects, objects, indirect objects, are like arguments
    Intransitive verbs are like functions that don’t take an argument
    Or, it is implicit (the subject)
    Functions like verbs imply actions that produce effects
    Person A: He ran for office.
    Person B: And ... ?
  • 15. Expressions
    Expressions are like phrases that combine nouns and verbs
    5
    (5 + 10) / 36
    “Tina” . “ is my cat”;
    file($url)
    $foo
    All expressions result in a value
    5
    0.4166666 ...
    Tina is my cat
    [the array of the file]
    [whatever $foo was last set to]
  • 16. Statements
    Statements are like sentences. They combine one or more expressions.
    $my_cat = “Tina”;
    $x = 2+2;
    They say something about something
    My Cat is Tina.
    $foois 2+2 (is 5)
    The verb “to be” is an assignment operator ...
    They are always punctuated by a semi-colon
  • 17. Operators
    Expressions and statements are built out of words by combining them with grammatical words, such as prepositions and conjunctions
    Iam in the house.
    I own a catanda dog.
    Operators are like the grammatical words
    They don’t have meanings, they have functions
    They don’t reference values (i.e. data), they do things with values
  • 18. Operators
    Arithmetic
    Addition, subtraction, division, multiplication, etc.
    String
    Concatenation
    Assignment
    X is Y
    Logical
    Is X Y?
    Is X related to Y in some specified way?
  • 19. Structures
    Structures, or control structures, are like stories or narrative patterns
    Built-in functions control conditions and iteration
    Repetition and branching
  • 20. Conditions
    if / elseif/ else
    if ($x == ‘foo’) {
    // do something
    } elseif ($x == ‘bar’) {
    // do something else
    } else {
    // do something else
    }
  • 21. Iteration
    foreach()
    while()
  • 22. Summary
    Values are like meanings
    Variables are like nouns
    Functions are like verbs
    Operators are like grammatical words
    These are combined to form expressions and statements
    Statements are structured in stories, or algorithms with control structures
  • 23. Exercise
    Create directory for today
    Copy rex.php into it
    Let’s revisit the program and use control structures to format the text
    Use foreach() to loop through the file
    Use IF statements to grab what we want
    Format the text with tags
  • 24. Two new functions
    preg_match($pattern, $string)
    Two arguments
    A regular expression pattern (between slashes “/.../”)
    A string to apply the expression to
    preg_replace($pattern,$replacement,$string)
    Three arguments
    A regular expression
    A something to replace the matched string with
    A string to apply the expression to
  • 25. Regular Expressions
    . = any character
    + = one or more
    * = 0 or more
    ^ = beginning of the string
    $ = end of the string
    [A-Za-z] = character set of all letters
    () = something to be replaced
  • 26. Assignment
    Grab the Oedipux text
    Trim the leading and trailing HTML tags
    Reformat each line using either DIV or P elements
    Create an appropriate CSS stylesheet for the text