Character Functions.docx

Character Functions.docx

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CharacterFunctions

Chapter1

CharacterFunctions

Chapter1:

CharacterFunctions29

Explanation

Thisstraightforwardprogramdemonstrateseachofthe"NOT"characterfunctions.Aswithmostcharacterfunctions,becarefulwithtrailingblanks.Noticethatthelastobservation（"ABC"）containsonlythreecharactersbutsinceSTRINGisreadwitha$5.informat,therearetwotrailingblanksfollowingtheletters'ABC'.Thatisthereasonyouobtainavalueof4forallthefunctionsexceptNOTDIGIT,whichreturnsa1（thefirstcharacterisnotadigit）.

AlistingofthedatasetNEGATIVEisshownnext:

ListingofDataSetNEGATIVE

NOT_ALPHA_NOT_NOT_NOT_

STRINGNUMERICALPHADIGITUPPER

ABCDE0010

abcde0011

abcDE0011

123450101

:

#$%&1111

ABC4414

FINDandFINDC

ThispairoffunctionssharessomesimilaritiestotheINDEXandINDEXCfunctions.FINDandINDEXbothsearchastringforagivensubstring.FINDCandINDEXCbothsearchforindividualcharacters.However,bothFINDandFINDChavesomeadditionalcapabilityovertheircounterparts.Forexample,thispairoffunctionshastheabilitytodeclareastartingpositionforthesearch,thedirectionofthesearch,andtoignorecaseortrailingblanks.

Function:

FIND

Purpose:

Tolocateasubstringwithinastring.Withoptionalarguments,youcandefinethestartingpointforthesearch,thedirectionofthesearch,andignorecaseortrailingblanks.

Syntax:

FIND（character-value,find-string<,'modifiers'><,start>）

30SASFunctionsbyExample

character-valueisanySAScharacterexpression.

find-stringisacharactervariableorstringliteralthatcontainsoneormorecharactersthatyouwanttosearchfor.Thefunctionreturnsthefirstpositioninthecharacter-valuethatcontainsthefind-string.Ifthefind-stringisnotfound,thefunctionreturnsa0.

Thefollowingmodifiers（inupper-orlowercase）,placedinsingleordoublequotationmarks,maybeusedwithFIND:

iignorecase.

tignoretrailingblanksinboththecharactervariableandthe

findstring.startisanoptionalparameterthatspecifiesthepositioninthestringtobeginthesearch.Ifitisomitted,thesearchstartsatthebeginningofthestring.Ifitisnon-zero,thesearchbeginsatthepositioninthestringoftheabsolutevalueofthenumber.Ifthevalueispositive,thesearchgoesfromlefttoright;ifthevalueisnegative,thesearchgoesfromrighttoleft.Anegativevaluelargerthanthelengthofthestringresultsinascanfromrighttoleft,startingattheendofthestring.Ifthevalueofstartisapositivenumberlongerthanthelengthofthestring,orifitis0,thefunctionreturnsa0.

Examples

FortheseexamplesSTRING1="Hellohellogoodbye"andSTRING2="hello"

FunctionReturns

FIND（STRING1,STRING2）7

FIND（STRING1,STRING2,'I'）1

FIND（STRING1,"bye"）17

FIND（"abcxyzabc","abc",4）7

FIND（STRING1,STRING2,"i",-99）7

Chapter1:

CharacterFunctions31

Function:

FINDC

Purpose:

Tolocateacharacterthatappearsordoesnotappearwithinastring.Withoptionalarguments,youcandefinethestartingpointforthesearch,thedirectionofthesearch,toignorecaseortrailingblanks,ortolookforcharactersexcepttheoneslisted.

Syntax:

FINDC（character-value,find-characters

<,'modifiers'><,start>）

character-valueisanySAScharacterexpression.

find-charactersisalistofoneormorecharactersthatyouwantto

searchfor.

Thefunctionreturnsthefirstpositioninthecharacter-valuethat

containsoneofthefind-characters.Ifnoneofthecharactersare

found,thefunctionreturnsa0.Withanoptionalargument,youcanhave

thefunctionreturnthepositioninacharacterstringofacharacterthatisnotinthefind-characterslist.

modifiers（inupper-orlowercase）,placedinsingleordoublequotationmarks,maybeusedwithFINDCasfollows:

iignorecase.

tignoretrailingblanksinboththecharactervariableandthe

find-characters.vcountonlycharactersthatarenotinthelistoffindcharacters.Oprocessthemodifiersandfindcharactersonlyoncetoaspecificcalltothefunction.Insubsequentcalls,changestotheseargumentswillhavenoeffect.

startisanoptionalparameterthatspecifiesthepositioninthestringto

beginthesearch.Ifitisomitted,thesearchstartsatthebeginningofthestring.Ifitisnon-zero,thesearchbeginsatthepositioninthestringoftheabsolutevalueofthenumber.Ifthevalueispositive,thesearchgoesfrom

32SASFunctionsbyExample

lefttoright;ifthevalueisnegative,thesearchgoesfromrighttoleft.A

negativevaluelargerthanthelengthofthestringresultsinascanfromrighttoleft,startingattheendofthestring.Ifthevalueofstartisapositivenumberlongerthanthelengthofthestring,orifitis0,thefunctionreturnsa0.

Note:

Youcanswitchthepositionsofstartandmodifiersandthefunctionwillworkthesame.

Examples

FortheseexamplesSTRING1="ApplesandBooks"andSTRING2="abcde"

FunctionReturns

FINDC（STRING1,STRING2）5

FINDC（STRING1,STRING2,'i'）1

FINDC（STRING1,"aple",'vi'）6

FINDC（"abcxyzabc","abc",4）7

Program1.14:

UsingtheFINDandFINDCfunctionstosearchforstrings

andcharacters

***Primaryfunctions:

FINDandFINDC;

DATAFIND_VOWEL;

INPUT@1STRING$20.;

PEAR=FIND（STRING,"Pear"）;

POS_VOWEL=FINDC（STRING,"aeiou",'I'）;

UPPER_VOWEL=FINDC（STRING,"aeiou"）;

NOT_VOWEL=FINDC（STRING,"AEIOU",'IV'）;

DATALINES;

XYZABCabc

XYZ

AppleandPear

;

PROCPRINTDATA=FIND_VOWELNOOBS;

TITLE"ListingofDataSetFIND_VOWEL";

RUN;

Chapter1:

CharacterFunctions33

Explanation

TheFINDfunctionreturnsthepositionofthecharacters"Pear"inthevariableSTRING.Sincetheimodifierisnotused,thesearchiscase-sensitive.ThefirstuseoftheFINDCfunctionlooksforanyupper-orlowercasevowelinthestring（becauseoftheimodifier）.Thenextstatement,withouttheimodifier,locatesonlylowercasevowels.Finally,thevmodifierinthelastFINDCfunctionreversesthesearchtolookforthefirstcharacterthatisnotavowel（upper-orlowercasebecauseoftheimodifier）.

Program1.15:

DemonstratingtheomodifierwithFINDC

***Primaryfunction:

FINDC;

DATAO_MODIFIER;

INPUTSTRING$15.

@16LOOK_FOR$1.;

POSITION=FINDC（STRING,LOOK_FOR,'IO'）;

DATALINES;

CapitalAhereA

LowerahereX

AppleB

;

PROCPRINTDATA=O_MODIFIERNOOBSHEADING=H;

TITLE"ListingofDataSetO_MODIFIER";

RUN;

Explanation

InthefirstcalltoFINDC,thevalueofLOOK_FORisanuppercaseA.Sincetheomodifierwasused,changingthevalueofLOOK_FORinthenexttwoobservationshasnoeffect—thefunctioncontinuestolookfortheletterA.NotethatanotheruseofFINDCinthisDATAstepwouldnotbeaffectedbytheprevioususeoftheomodifier,evenifthenameof

thevariable（inthiscasePOSITION）werethesame.Theomodifierismostlikelyusefulinreducingprocessingtimewhenloopingthroughmultiplestrings,lookingforthesamestringwiththesamemodifiers.ThelistingofdatasetO_MODIFIERbelowshowsthat,eventhoughtheLOOK_FORvaluewaschangedtoXinthesecondobservationandBinthethirdobservation,thefunctioncontinuestosearchfortheletterA.

34SASFunctionsbyExample

ListingofDataSetO_MODIFIER

STRINGLOOK_FORPOSITION

CapitalAhereA2

LowerahereX7

AppleB1

Chapter1:

CharacterFunctions43

FunctionsThatExtractPartsofStrings

Thefunctionsdescribedinthissectioncanextractpartsofstrings.Whenusedonthelefthandsideoftheequalsign,theSUBSTRfunctioncanalsobeusedtoinsertcharactersintospecificpositionsofanexistingstring.

Function:

SUBSTR

Purpose:

Toextractpartofastring.WhentheSUBSTRfunctionisusedontheleftsideoftheequalsign,itcanplacespecifiedcharactersintoanexistingstring.

Syntax:

SUBSTR（character-value,start<,length>）

character-valueisanySAScharacterexpression.

startisthestartingpositionwithinthestring.

lengthifspecified,isthenumberofcharacterstoincludeinthe

substring.Ifthisargumentisomitted,theSUBSTRfunctionwillreturnallthecharactersfromthestartpositiontotheendofthestring.

Ifalengthhasnotbeenpreviouslyassigned,thelengthoftheresulting

variablewillbethelengthofthecharacter-value.

Examples

Fortheseexamples,letSTRING="ABC123XYZ"

FunctionReturns

SUBSTR（STRING,4,2）"12"

SUBSTR（STRING,4）"123XYZ"

SUBSTR（STRING,LENGTH（STRING））"Z"（lastcharacterinthestring）

44SASFunctionsbyExample

Program1.21:

Extractingportionsofacharactervalueandcreatingacharactervariableandanumericvalue

***Primaryfunction:

SUBSTR

***Otherfunction:

INPUT;

DATASUBSTRING;

INPUTID$1-9;

LENGTHSTATE$2;

STATE=SUBSTR（ID,1,2）;

NUM=INPUT（SUBSTR（ID,7,3）,3.）;

DATALINES;

NYXXXX123

NJ1234567

;

PROCPRINTDATA=SUBSTRINGNOOBS;

TITLE'ListingofDataSetSUBSTRING';

RUN;

Explanation

Inthisexample,theIDcontainsbothstateandnumberinformation.ThefirsttwocharactersoftheIDvariablecontainthestateabbreviationsandthelastthreecharactersrepresentnumeralsthatyouwanttousetocreateanumericvariable.Extractingthestatecodesisstraightforward.Toobtainanumericvaluefromthelast3bytesoftheIDvariable,itisnecessarytofirstusetheSUBSTRfunctiontoextractthethreecharactersofinterestandtothenusetheINPUTfunctiontodothecharactertonumericconversion.AlistingofdatasetSUBSTRINGisshownnext:

ListingofDataSetSUBSTRING

IDSTATENUM

NYXXXX123NY123

NJ1234567NJ567

Chapter1:

CharacterFunctions45

Program1.22:

Extractingthelasttwocharactersfromastring,regardless

ofthelength

***Primaryfunctions:

LENGTH,SUBSTR;

DATAEXTRACT;

INPUT@1STRING