Chapter1FasttracktoPHPProgramming

Whatisprogramming?Haveyoueverbeengivenalistofthingstodoorlookedatinstructions?Wellthatiswhatprogrammingis,onlythelistofthingstodoorinstructionsarewritteninawaythatacomputercanunderstandthem.WewillbeexploringthePHP[https://en.wikipedia.org/wiki/PHP]programminglanguage.ForusthemainpointtorememberiswhatPHPdoesforus.InanutshellPHPcreatesHTMLcode.Whatisafasttrack?Itmeanswewillcoveronlywhatweneedjustbeforeweneedit.Thegoalistogainageneralunderstandingnotacompleteunderstanding.Thecompleteunderstandingcomeswithtime.

Computersonlydofourthings:

1. Input–Acceptinputintothecomputerviakeyboard,mouse,touchscreen,voicecommands.

2. Process–AprogramwillprocesstheInputithasbeengiveninsomefashionfromsimpleadditiontodeterminingyourcurrentlocationbasedonthegpscoordinatesitreceives.

3. Output–Thecomputerprovidesuswithoutput,generallytoourcomputerscreen,printedonpaperorspeakerstonameafew.

4. Storage–Thecomputerallowsustosaveinformation,documents,picturesevenyourcontactlistareallexamplesofstorage.

Evenmoreamazingiscomputersdoallthesethingsbyunderstandingifanelectricalswitchisturnedonoroff!Fromabasicsenseitistheseriesofswitchesthatmakeupwhatiscalledabyteanditisthepatternofhowtheyareturnedonandoffdictateswhattheymean.ForexampleZeroisusedtorepresentoffandOneisusedtorepresenton.Sothis:

01000001[https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiDuJ-R_4bUAhVi_4MKHWWEDY0QFggoMAA&url=https%3A%2F%2Fwww.jpl.nasa.gov%2Fedu%2Fpdfs%2Fphases_chart.pdf&usg=AFQjCNGoOlgxYfkqpkDiRox9ETB8AzrMQw&sig2=a3JDZ1s_An9ufSjZSRUAAw]

representsthecapitalletterAwhenusingASCIItext[https://en.wikipedia.org/wiki/Wikipedia:ASCII].Thecomputerlooksupinatablewhatthatrepresentsthendisplaythecharacteritistoldto.Prettyamazinghowmanyelectricswitchesareturnedonandoffinjustasimpletextmessage!

Soeverythingacomputerdoesisbecausesomeonehaswrittenaseriesofinstructionstotellthecomputerwhattodo.PHPisconsideredahighlevellanguagewherewedon’thavetoworryabouttheonesandzerosbutinsteadwelearnthesyntaxandstructureoftheprogramminglanguage.

WeputPHPinstructionsinsidethePHPelementandtheendresultwillbeHTML.Forexample(meaningauselessexampleotherthantodemonstratethepoint)wecouldhavePHPsayhello(oldfashionedfirstprogramwouldbeHelloWorld)orinthecaseoftheexamplebelow"What'sup?".

Thisishowitwilllookinthebrowser:

<?phpThePHPTag

OpeningTag

?>ClosingTag

Likeallthehtmlelementsthephpelementhasanopeningandclosingtag

andmoreimportantlyifwelookatthebrowserssourcecodethisiswhatwesee.

Soitmaybeareallysimpleexampleandnotverypracticalbutthereisalotgoingon.Let'sstartwiththePHPwordprintwhichisbuiltintoPHPandjustcauseswhatevercomesafterittobecomepartoftheHTMLcode.OkIneedtotakeastepbackanddescribewhathappenswhenyourequestaPHPpageintheURL.

Let'sfollowthesteps:

1. Youtypeaurlintoyourbrowserwindow,intheaboveexamplehttp://bob.com/home.php.Thebrowserthengoestotheserverthathoststhatwebsite.

2. Theserverthenlooksforthefilehome.php(justlikeyoulookforfilesonyourcomputer).Whenitfindsthefileitnoticesithasa.phpextensionandsayswoohooaPHPfile(okmaybeitdoesnotactuallysaythat).TheserverthenreadstheentirecontentsofthefileexecutingeachlineofPHPcodeoneatatime.

3. ThePHPinterpretercreatesafile(stillcalledhome.php)thathasnothingbutHTMLcodeinitthatlooksjustlikethebrowserssourcecodeabove.SoitexecuteseachPHPinstructionthatyouhavegivenit.

4. Theservertakestheoutputfilehome.phpthathasnothingbutHTMLinitandsendsitbacktothe"clients"computer(yourcomputer)sothatyourwebbrowsercandisplayit.

Okprettyneatbutlet'sfaceit,ifthatisallPHPcandowemightaswelljustwritetheHTMLdirectlyandsaveourselvesthetrouble.Iamhopingthoughthatlittleexamplemakessenseandofcoursewearegoingtohavemoredetailedinstructionsbutwehavetolearntocrawlbeforewecanrun.

Allprogramsneedvaluesorinputthatwehavetopassintotheprograminsomefashion.Let'sjuststartwithvariables.LetusstartwithmathandthePythagoreantheorem[http://www.basic-mathematics.com/pythagorean-theorem.html]whichstates:

c2=a2+b2

noticeIwroteitbackwardssincethatishowweassignavalueinprogrammingversusthemathclasswayofa2+b2=c2.Scaredyet?Don'tworry.InBuildingTradesIlearnedthisasthe3,4,5triangletoseeifthebuilding'scornerissquare.

[https://www.google.com/maps/search/ocean+county+vocational+school/@39.9836687,-74.1876238,771a,35y,270h,39.28t/data=!3m1!1e3]TechnicallyIhelpedbuildthewallfromthecornertothedoorbutwehadtobesquareorthedoorwouldnotwork(gladtoseeitsstillstandingfrom1979)

ThewayIlearneditwasthatifyoumeasure4feetononeside(a)andputapencilmarkthere.Nextmeasure3feetontheotherside(b)andputapencilmarkthere.Nowmeasurethedistancebetweenthetwopencilpointsaslongasyourbuildingissquareitwillmeasure5feet.Oksolet'sprogram3and4intotheformulainPHPtoseeifctrulyisfiveasmyshopteachertaughtme.

andweuploadourfiletotheserverandthisiswhatshowsupinthebrowser!

OkIhaveneverusedthesquarerootmethod[http://php.net/manual/en/function.sqrt.php]builtintoPHPsoIhadtogoogleit.Clearasmud?Welllet'strytoclearthingsupabit.ThePHPline:

$a=4;iscalledanassignmentstatementtobeofficial.Theletteraiscalledavariable.AllvariablesinPHPbeginwitha$sign(prettymuchtheonlylanguageIknowofthatusessuchaconvention).Whathappenswhenwhenaprogramminglanguagecreatesavariableisthatitmakesaboxinthecomputersmemoryandgivesthatboxthenameyoutolditto.

OncePHPhastheboxitwilltakewhateveristotherightoftheequalsignandputthatvalueinthebox,beitanumber,word,imagewhatever.Inourexamplethenumber4

Thecomputerwilldothiswiththevariablebaswell.Itdoesthesamethingforthevariableconlyitwillcalculatethevaluefirstfollowingthestandardrulesformath(PEMDAS)[http://www.coolmath.com/prealgebra/05-order-of-operations/05-order-of-operations-parenthesis-PEMDAS-01]

NowletusexplorethatPHPmethodcalledprintwhichwillprinttothefilewhatevercomesafterit.Ihavealotofthingstoexplain.Ihaveusedsinglequotes.YoucanusedoublequoteshowevertobeconsistentItrytousesinglequotesforPHPanddoublequotesforHTML.NoticeinmyfirstexampleIprinted

print'<p>What\'sup?</p>';Oktheoutsidesinglequotesmakesenseastheprintmethodwillprintwhateverisinsidethequotes.SinceIwantedtoprintasinglequoteinsideofsinglequotesIhadto'escape'thequotewitha\backslashwhichmeansignorethequoteandjustprintit.JusttomakelifeconfusingIcouldhaveuseddoublequotesontheoutsideanditwouldproducethesameHTMLoutput.

print"<p>What'sup?</p>";Idon'tneedtoescapethesinglequoteinthiscase.Eitherwayworksjustrememberthatwhateveryoustartandendwithcannotbeontheinside.ToreallymesswithyourbrainIcoulddothis:

print'<p>What'."'".'sup?</p>';Theinnerblockwithfivequotesisreallyadoublequote,singequote,doublequotebutitfollowstherulesIdescribedabove.Programmingcanbefunkyattimesespeciallywhenitcomestoquotes.

Whatisupwiththeperiodsbytheway?InPHPtheperiodsareusedtoaddtexttogetherwhichwecallconcatenation.Letslookatanexample.

Line13willconcatenate4and3togetherastextsoitwilldisplayas43.Line14willadd4and3asnumberssoitwilldisplay7.

Let'slookatthesourcecodesowecanseewhatPHPcreated.

NoticethatallthePHPcreatedHTMLisonline9eventhoughinthecodetheyareonseparatelines.ThereasonisthatwenevertoldPHPtoputalinebreakin.ComputersonlydowhattheyaretoldandwenevertoldPHPtostartanewline.Youdon'tneedtoasnewlinesareforhumansbutifyouwantedtowecandothatbyprintinga\n.Ofcoursethismakestheuseofquotesevenmoreconfusing.HereIusedsingleanddoublequotes.

Let'slookattheresults.

Theendoflinemarkneedstobeprintedindoublequotesoritdoesnotworkasintended.Noticetheclosingbodyelementhasmovedtothenextlinebutthe\njustprintedonourpage.Thereisnotmuchpointinwonderingwhyit(printed\nwheninsinglequotes)islikethisbutitiswhatitis.Itisagoodexampleofwhenwemaynotunderstandwhyitislikethatbutweunderstandwhatitdoesandwecanacceptthat.

YoucanuseabuiltinPHPconstantcalledPHP_EOLwhichwillnotrequirequotesandwhichisjustthebestthingtodo.

Ionlymentionedallthisasawayofexplanationandintroduction.TheonlytimeIhavePHPputintheendoflinebreakiswhenIamhavingtroublewithmycodeandIcannotfigureitout.ItmakesiteasiertoseewhattheHTMLcodelookslikethatPHPcreated.

SowehavevariablesinPHPwhichcanbenumbersbuttheycanalsobestrings(text,words,lettersetc.).ForexampleIhavemyheadingtextinavariable.

Thiswillprintthetextinsidetheheadingone.AsareminderthisisasimpleexampleandnotverypracticalbutIamusingittodemonstrateapoint.Howeverhavingsaidthatifyouuseaframeworktocreateyourwebsitethisisprettymuchwhattheydo.

Allrightwehavesomebasicsdown:

1. PHPcreatesHTML.2. Variablesholdvaluesinthecomputer'smemory.3. Variablenamesallbeginwitha$sign.

4. Variablenamescannotcontainblankspacesorspecialcharactersotherthantheunderscore(okthisoneisnew)andshouldbeselfdocumentingmeaningIshouldnothavetoaskwhatthevariableisfor.

5. Variablescancontainnumbers,textandabunchofotherthings.6. Textiscalledastring.7. Quotesarefunky,generallyinPHPwetrytousesinglequotesaroundallstring

variables.8. Youcanhavesinglequotesontheoutsidewithdoublequotesontheinside.9. Youcanhavedoublequotesontheoutsidewithsinglequotesontheinside.10. Ifyouneedtobreaktheabovequoterulesyouwillhavetoescapethequotesonthe

insidewitha\character.11. Aperiodisusedtoconcatenatetexttogether.12. Aplussignwilladdtwonumbers(wecanguessabout-,*,/).13. ToaddlinebreaksinoursourcecodeweneedtoprintPHP_EOL.

Let'sjumpahead.Therearethreemainprogrammingstructuresinallprogramminglanguages:

Sequence–eachlineofcodeisexecutedoneaftertheotherinorder.

Selection–allowsustochoosewhichlinesofcodegetexecutedmeaningwecanskiplines.

Repetition–allowsustokeepdoingthesamelinesofcodeoverandoveragainasmanytimesasweneedto.

Let'sstartSequence,prettymuchallcodeisdoneintheorderthatitappears.Computerdon’tjumparoundintheirlistoftaskstheyneedtodo.SothesethreelinesofPHPcodejustprintsoutthethreelinesofHTMLinthesameorder.SincewehavenotprintedaEOL(endofline)marktheywillbeallinonelinebutthebrowserwilldisplaythemseparately(giveitatry).

print'<h1>Thisisaheading</h1>';

print'<p>Thisisaparagraph.</p>';

echo'<p>Youcanprintorechothetextyouwanttodisplay</p>';Thiswillshowupononeline(okinthisdocumentitwordwrapsbutwhenyouviewthepagesourceitwillnotwordwrap)likethisinthebrowserssourcecode:

<h1>Thisisaheading</h1><p>Thisisaparagraph.</p><p>Youcanprintorechothetextyouwanttodisplay</p>IwanttotalkabouttheRepetitionprogrammingstructurewhichwillrepeatlinesofcodetillyoutellittostop.LetmeshowyouthePHPsyntaxforaforloop:

for(variable;condition;increment){

//Dotheseinstructions

}NoticethedoubleslashesarePHPversiontohavecomments.Youcanhaveasmanyinstructionsasyouneed.Letmeaddsamplecodethatwillprintthatline100times:

for($i=0;$i<100;$i++){

print'<p>Iwillnottalkinclass.</p>';

}Let'slookataflowchart,whichIthinkyoucanfollowalongwith.TheSquareboxesrepresentalineofcodethatisdoingsomething.ThediamondshaperepresentsaBoolean(Booleanisfancyforayesornoquestion)questionyouhavetoanswer.Thelinesshowyouwhichwaytogonext.

Westartbyinitializingourvariable$itozero.Thismeanswewillstartwiththenumberzeroandgofromthere.Normallyaonelettervariablenameisbadbut$iisacommononeoftenusedinloopsforindex.Othercommonloopvariablesarecalledj,k,andc(jbecauseitcomesafteri,cforcountandkforkount).Sowhenweinitializeavariablethecomputercreatesaboxinitsmemoryandputsthevalueinit.

Nowweanswerthequestion.Isilessthan100?Sincetheanswerisyeswegointotheloopanddothestatementsfoundthere.Inthiscasewehavejustone:

Iwillnottalkinclass.

Wenowgotothenextboxwhichsaystoincrementthevalue.Wehave$i++whichisashortcutfor$i=$i+1.

Nowweanswerthequestionagain.Isilessthan100?Sincetheanswerisyeswegointotheloopanddothestatementsagain.Wekeepdoingthisuntilibecomes100.Sowheniis99wedothestatementsthenweincrementiby1to100

Nowweanswerthequestionagain.Isilessthan100?Sincetheanswerisnowedon’tgointotheloopandwemoveontothenextstatementaftertheloop.

Canyouseewhatthisloopwoulddo?

for($i=1;$i<=6;$i++;){

print'<h'.$i.'>Iwillnottalkinclass.</h'.$i.'>';

}Itwillprintoutall6headinglevels.Giveitatry.Istartedwithadifferentstartingpoint,oneinsteadofzero.Myconditionhadlessthanorequaltoinsteadofjustlessthan.OfcourseIwasalsoprintingoutthevalueofieachtimetocreatethedifferentHTMLelements.

Oksomaybetheforloopexamplesarenotsomethingyouwouldusebuttheyaregoodexamplesofthepotentialuses.Inthisclassweactuallydon’tusetheforloopallthatmuchbutweusetheconceptallthetime.Letmeleadyouthroughanotherexample.

Wehavetalkedaboutvariablesandwehavelearnedthat,wecanassignavaluetoavariable,wecanprintavariable,wecanusethevariableinaformulaandwecanchangethevalueofavariable.Thereisavariablethatcanhavemorethanonevalue,itiscalledanarray.Youcanthinkofanarrayasatable.Forexamplehereisatableoranarrayofmystudents:

TocreatethisinPHPcodewewouldinitializethevariabletobeanarraywiththevaluesinitlikethis:

$students=array('Adam',Bonnie,'Carol','David');Therealquestionishowdoweaccessorprintthesevariables?Atemporarywaytoprintyourarrayjusttoseeifitworksistouseprint_rmethodmadespecificallyforarrays.

print'<p>Students</p><pre>';

print_r($students);

print'</pre>';

Thiswouldprintitoutlikethis:

Thisisofcoursenotthewaytoprintyourarrayonawebpagebutitisahandywaysothatyoucan"see"whatisinthecomputersmemory.Youmaybeabletoguessthatwecanaccesseachvaluebyitsindexnumber.Ofcoursetheystartwithzerosincecomputersliketostartwith0.Wecanprintoutonevaluebyputtingtheindexnumberinthesquarebrackets:

print '<p>' . $students[0] . '</p>';

Youcouldputthisintoaforloopandprintthemalloutbyreplacingthe0withan$ivariable

for ($i=0;$i<count($students);$i++){

print '<p>' . $students[$i] . '</p>';

}

HoweversinceitissocommontousearraysinPHPwehaveaspecialloopstructurejustforthem.Itiscalledaforeachloopandthisiswhatweshoulduseforarrays.

Thesyntaxfortheforeachloopis:

foreach(array-variable-nameasone-row-of-the-array){

//Dotheseinstructions

}

Trytonameyourarraysinthepluralform,iestudents,cars,people.Thenusethesingularnamefortheasvariable,iestudent,car,personasitmakesforeasierunderstandingofthecode.

Let'slookattheforeachflowcharttoseeifyoucanfollowthrough:

Inthiscasewehaveanarrayvariableandthequestiontoaskis:Istherearowofdata?Ifyeswedothestatements.Theincrementisautomaticastheforeachloopwillautomaticallygotothenextrecordtilltherearenomore.Let'slookatsomesamplecode:

<?php

$students=array('Adam','Bonnie','Carol', 'David');

print '<h1>Class List</h1>';

print '<ol>';

foreach ($students as $student){

print '<li>' . $student . '</li>';

}

print '</ol>'; ?>

Acoupleofthingstonotice.SinceIamprintinganorderedlistIneedtoprinttheopenandclosingolelementsoutsideoftheloop.TheHTMLcodethatwillberepeatedisthelistitem(li)insidetheloop.Seehowthevariable$studentisfortheonestudentatatime.Theoutputfromthiscodelookslikethis:

WiththecorrespondingHTMLsourcecodecreatedlookinglikethis(wedidnotputinanyEOF)

Clearasmud?IamtryingtotakequantumleapswithyourunderstandingandIamhopingyouareabletofollowalongwiththebasicsthatIamgivingyou.Aonecolumnarrayisfairlystraightforwardbutgenerallywealwayshavemorethanonecolumn.Iwanttoshowyouatwocolumnarray(morethantwoisreallyjustthesamesyntaxjustmoreofit).Tomakeatwocolumnarrayyoujusthaveeacharraybox(likewereAdamwasinthebox)beanarrayitself.Youcanthinkofanarraywithmorethanonecolumnasanarrayinanarray.HereisthecodetocreateatwocolumnarrayofthefreezeoverdatesforLake

Champlain.Ihavetriedtohelpyoupictureitasanarraywithmanyarraysinsideit.Itmaytakeawhiletomakesense.

$freezeDates = array( array(2000, 'not closed'), array(2001, '2001-03-02'), array(2002, 'not closed'), array(2003, '2003-02-15'), array(2004, '2004-01-27'), array(2005, '2003-03-08'), array(2006, 'not closed'), array(2007, '2007-03-02'), array(2008, 'not closed'), array(2009, 'not closed'), array(2010, 'not closed'), array(2011, 'not closed'), array(2012, 'not closed'), array(2013, 'not closed'), array(2014, '2014-02-12'), array(2015, '2015-02-16')

);

Noticehoweachrow(exceptforthelastone)hasacommaattheend.Asareminder,tocreateaone-dimensionalarray(onecolumnarray)itwouldbe:

$students=array('Adam','Bonnie','Carol','David');

So'Adam'wasoneelementinthearrayjustlikearray(2000,'notclosed')isoneelementinthearray.Wearejustmakingtheoneelementbigger.Itisalittlebitmorecomplicatedwhenloopingthroughthemulticolumnarrayasyouneedtospecifywhichcolumntodisplay.Remembertostartwithzero.

foreach ($freezeDates as $freezeDate) {

print '<p>' . $freezeDate[0] . ' – ' . $freezeDate[1] . '</p>';

}

Makesense?Arraysareusedheavilyintheweb.Howwepopulatethearraychangesasyougainmoreexperiencebutloopingthroughthearrayisthesame.Itwillbehardatfirstbutonceyouwrapyourheadarounditwon'tbeasbadasitsoundsthefirsttime.Thisvideomayhelp(especiallywhenyoumakeamistake)

CodeWalkThrough:https://www.youtube.com/watch?v=9WEIGziEylo&list=PLxWIQk1hqg09WQMlrnyjK8sVsrdoqo8lJ&index=14&t=545s

SelfTestQuestions

1. ThePHPcommandprintcauseswhateverthatcomesafterittobecome__________?2. Thiswillprint:

a. print1+2*3; b. print10/2-3; c. print8+20*2-6; d. print(8+2)*(6-2)+2;

Forthenextfewquestionsusethesevalues:$a=1;$b=2;$c=3;

e. print$a.$b f. print($a+$b)*$c g. print$a+$b*$c

3. T(true)orF(false)a. print'WelcometotheJungle'; b. print"<h2>WelcometotheJungle</h2>"; c. echo'<p>WelcometotheJungle</p>'; d. print'Let'sGoFishing!'; e. print'Let\'sGoFishing!'; f. echo"Let'sGoFishing!";

4. WriteaPHPstatementtoprintyourname. 5. WriteaPHPstatementtoprintaheadingoneelementwiththetextDon'tMakeMe

Think6. Giventhisarray$numbers=array(3,33,37,51,57,21);

whatwillthisstatementprint?print'<p>Number:'.$numbers[3];

7. Createanarrayforyourtopthreefavoriteplaces,printthearray.

ChallengeQuestions

1. Personal Information Write some php code that stores the following information in respective variables and then prints it on the page.

- Your name - Your address, with city, state and ZIP - Your telephone number - Your college major

2. Sales Prediction

A company has determined that its annual profit is typically 23 percent of total sales. Write some php code that will display the profit made from an amount that is stored as a variable. Print the profit on screen.

3. Distance Traveled Assuming there are no accidents or delays, the distance that a car travels down the interstate can be calculated with the following formula: Distance = Speed X Time A car is traveling at 70 miles per hour. Write some php code that displays the following:

- The distance the car will travel in 6 hours - The distance the car will travel in 10 hours - The distance the car will travel in 15 hours

4. Day of the Week Write some php code that uses an array to print the day of the week based on a number, where 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday, 7 = Sunday.

5. Roman Numerals Write some php code that prints a roman numeral from 1 to 10 depending on the value of another variable. (Hint: store the roman numerals in an array)

AnswerstoChallengeQuestions

1. Answer: <?php $name = “Alec”; $address = “388 College St, Burlington Vt, 05405”; $number = “123-456-7890”; $major = “Computer Science”; print $name; print $address; print $number; print $major; ?> 2. Answer:

<?php $totalSales = 100; print 0.23 * $totalSales; ?>

3. Answer: <?php $speed = 70; print $speed * 6; print $speed * 10; print $speed * 15; ?> 4. Answer:

<?php $array = [Monday,Tuesday,Wednesday,Thursday,Friday,Saturday,Sunday]; $day = 1; $print $array[$day]; ?>

5.Answer:

<?php $number = 5; $romanNumerals = [‘I’, ‘II’, ‘III’, ‘IV’, ‘V’, ‘VI’, ‘VII’, ‘VIII’, ‘IX’, ‘X’]; print $romanNumerals[$number - 1]; ?>