PHP variables represent data values and are like nouns. Functions represent actions and are like verbs. Operators combine values and functions to form expressions and statements. Control structures like if/else statements and loops structure programs like narratives. The document then discusses regular expressions and creating custom functions in PHP.

1. PHP 2MDST 3559: DataestheticsProf. Alvarado02/17/2011

2. BusinessVPN?

3. ReviewPHPVariables, Data Types, FunctionsSee Chapters 2 through 5 of Programming PHPTextEarlier we saw the text handled as a tree (CSS, jQuery)Tuesday we treated the text as an array, a simple linear sequence,

4. OverviewToday we will go back over the basics of PHP To provide a slightly different angle on the subjectTo help clarify some concepts for those new to programmingTo help clarify the “PHP way” for those with experienceThen we will cover two new topicsRegular ExpressionsCreating your own functions

5. PHP as a languagePHP is a programming langague (of course), but it has analogies to natural language as wellThere are parallels to the basic structures of human languagesWhich makes sense: Programming languages are designed to mediate between human and machine language

6. What are some elements of natural language?

8. Some Elements of Natural LanguageWordsMeaningsSentencesSomething is said of something elseParts of speech: nouns, verbs, prepositionsHeart of language as language, beyond mere signsParagraphs

9. PHP has all of these things

10. Values are MeaningsValues are pieces of dataLanguages are all about doing things with dataData comes in typesTypes include strings and numbersAlso Boolean values (true/false)Values are expressed literally and signified like so:“Hello, World!”5trueThese are the meanings of the language

11. Variables are NounsVariables 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 weirdBut they can be thought of as words that stand for collections, e.g.The Pittsburgh SteelersThe UVA student bodyThese phrases imply a structureAlbeit much more complicated than arraysBut not much: consider rosters ...

13. Functions are VerbsFunctions are like verbs$food = food_shop($me,$money,$humger_level)Like verbs, they may require arguments and imply a resultVerbs are action wordsConsider transitive versus intransitiveThey are not prefixed by $They are not case sensitiveThey are followed by parentheses

14. FunctionsVerbs have implicit arguments and effectsSubjects, objects, indirect objects, are like argumentsIntransitive verbs are like functions that don’t take an argumentOr, it is implicit (the subject)Functions like verbs imply actions that produce effectsPerson A: He ran for office.Person B: And ... ?

15. ExpressionsExpressions are like phrases that combine nouns and verbs5(5 + 10) / 36“Tina” . “ is my cat”;file($url)$fooAll expressions result in a value50.4166666 ...Tina is my cat[the array of the file][whatever $foo was last set to]

16. StatementsStatements are like sentences. They combine one or more expressions.$my_cat = “Tina”;$x = 2+2;They say something about somethingMy 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. OperatorsExpressions and statements are built out of words by combining them with grammatical words, such as prepositions and conjunctionsIam in the house.I own a catanda dog.Operators are like the grammatical wordsThey don’t have meanings, they have functionsThey don’t reference values (i.e. data), they do things with values

18. OperatorsArithmeticAddition, subtraction, division, multiplication, etc.StringConcatenationAssignmentX is YLogicalIs X Y?Is X related to Y in some specified way?

19. StructuresStructures, or control structures, are like stories or narrative patternsBuilt-in functions control conditions and iterationRepetition and branching

20. Conditionsif / elseif/ elseif ($x == ‘foo’) { // do something} elseif ($x == ‘bar’) { // do something else } else { // do something else}

21. Iterationforeach()while()

22. SummaryValues are like meaningsVariables are like nounsFunctions are like verbsOperators are like grammatical wordsThese are combined to form expressions and statementsStatements are structured in stories, or algorithms with control structures

23. ExerciseCreate directory for todayCopy rex.php into itLet’s revisit the program and use control structures to format the textUse foreach() to loop through the fileUse IF statements to grab what we wantFormat the text with tags

24. Two new functionspreg_match($pattern, $string) Two argumentsA regular expression pattern (between slashes “/.../”)A string to apply the expression topreg_replace($pattern,$replacement,$string)Three argumentsA regular expressionA something to replace the matched string withA 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. AssignmentGrab the Oedipux text Trim the leading and trailing HTML tagsReformat each line using either DIV or P elementsCreate an appropriate CSS stylesheet for the text