Transcript
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Introduction to ProgrammingLesson 1
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Objectives
Skills/Concepts MTA Exam Objectives
Understanding ComputerProgramming
Understand computer storageand data types (1.1)
Understanding Decision
Structures
Understand computer decision
structures (1.)
Understanding !epetitionStructures
Identi"y t#e appropriate met#od"or #and$ing repetition (1.%)
Understanding &'ception
and$ing
Understand error #and$ing (1.)
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*$gorit#ms
• *$gorit#m re"ers to a met#od "orso$ving prob$ems.
• Common tec#ni+ues "or representing
an a$gorit#ms, – -$oc#art
– Decision /ab$es.
Flowcharts and Decision Tables
0ore precise t#an natura$$anguages
Less "orma$ and easier touse t#an programming
$anguages
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-$oc#arts
• * oc#art is a grap#ica$representation o" an a$gorit#m.
Common Flowchart Smbols
Start or end o" an a$gorit#m
Process or computationa$ operation
Input or out operation
Decision ma2ing operation
Direction o" t#e o o" contro$
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-$oc#art &'amp$e
• * oc#art t#at compares to numbers,
Start
Input '
Input y
3 4 y5
Output'
Stop
Output
y
6o
7es
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Decision /ab$e
• Use"u$ "or $arge number o" conditions
• Compact and readab$e "ormat
• * decision tab$e to ca$cu$atingdiscount,
!"antit #$%
& ' ' '
!"antit #(%
7 7 6 6
!"antit #$%%
7 7 7 6
Disco"nt 89 1:9 189 :9
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Introducing C;
• 0icroso"t .6&/ -rameor2 – *n &'ecution &nvironment
– !eusab$e C$ass Libraries
– Language Compi$ers
• /#e C; Programming Language – Part o" t#e .6&/ -rameor2
– ig#<$eve$ Language
– Program needs to be compi$ed be"ore t#ey can bee'ecuted.
– Case sensitive
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&$ements o" a C; Program
• Se$ect common e$ements o" a C;program,
Data Tpes /ypes o" data in a program. Common data types are int(integers)= c#ar (sing$e c#aracter va$ue)= oat (oatingpoint va$ues).
)ariables Provides temporary storage during program e'ecution.int number > 1:?
Constants Data @e$ds #ose va$ue cannot be modi@ed.const int i > 1:?
Arras * co$$ection o" items in #ic# eac# item can be accessedby a uni+ue inde'.intAB numbers > 1= = %= = 8 ?
Operators Symbo$s t#at speci"y #ic# operation to per"orm onoperands be"ore returning a resu$t.
Methods 0et#ods are code b$oc2s containing a series o" statements.0et#ods can receive input via arguments and can return ava$ue to t#e ca$$er.
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Decision Structures
/#e i"Statement /#e i"<e$seStatement
/#e sitc#Statement
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/#e i" Statement
• /#e i* statement i$$ e'ecute a givense+uence o" statements on$y i" t#ecorresponding Eoo$ean e'pression
eva$uates to true.
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/#e i"<e$se Statement
• /#e i*+else statement a$$os your program to per"orm oneaction i" t#e Eoo$ean e'pression eva$uates to true and adiFerent action i" t#e Eoo$ean e'pression eva$uates to "a$se.
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/#e sitc# Statement
• /#e switch statement a$$os mu$ti<aybranc#ing. In many cases= using a sitc#statement can simp$i"y a comp$e' combination o"i"<e$se statements.
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!epetition Structures
/#e #i$e Loop
/#e do<#i$e Loop
/#e "or Loop
/#e "oreac# Loop
!ecursion
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/#e #i$e Loop
• /#e while $oop repeated$y e'ecutesa b$oc2 o" statements unti$ aspeci@ed Eoo$ean e'pression
eva$uates to "a$se.
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/#e do<#i$e Loop
• /#e do+while $oop repeated$ye'ecutes a b$oc2 o" statements unti$a speci@ed Eoo$ean e'pression
eva$uates to "a$se. /#e do+while $oop tests t#e condition at t#ebottom o" t#e $oop.
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/#e "or Loop
• /#e *or $oop combines t#e t#reee$ements o" iterationGt#einitia$iHation e'pression= t#e
termination condition e'pression=and t#e counting e'pressionGinto amore readab$e code.
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/#e "oreac# Loop
• /#e *oreach $oop is an en#ancedversion o" t#e "or $oop "or iteratingt#roug# co$$ections suc# as arrays
and $ists.
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!ecursion
• !ecursion is a programmingtec#ni+ue t#at causes a met#od toca$$ itse$" in order to compute a
resu$t.
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&'ception and$ing
• *n e'ception is an une'pected error conditiont#at occurs during program e'ecution.
• #en e'ception occurs= t#e runtime creates ane'ception object and Jt#rosK it.
• Un$ess you Jcatc#K t#e e'ception= t#e programe'ecution i$$ terminate.
• &'ceptions are an object o" t#e System.&'ceptionc$ass or one o" its derived c$asses.
– &'amp$e, Divide,-eroException e'ceptionobject is t#ron #en t#e program attempts todivide by Hero.
– &'amp$e, File'otFo"ndException e'ception
object is t#ros #en t#e program cannot @nda iven @$e.
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Un#and$ed &'ceptions
• #at #appens #en t#e @$ec,data.t't is not "ound in t#is code5
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and$ing &'ceptions it# try<catc#
• P$ace t#e code t#at t#ros t#ee'ceptions inside a tr b$oc2.
• P$ace t#e code t#at #and$es ane'ception inside a catch b$oc2.
• 7ou can #ave more t#an one catc#b$oc2s "or eac# try b$oc2. &ac# catc#
b$oc2 #and$es a speci@c e'ceptiontype.
• * try b$oc2 must #ave at $east a
catc# b$oc2 or a @na$$y b$oc2
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&'ception and$ing Samp$e
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/#e @na$$y E$oc2
• /#e .nall b$oc2 is used in association it# t#etry b$oc2.
• /#e .nall b$oc2 is a$ays e'ecuted regard$ess o"#et#er an e'ception is t#ron.
• /#e .nall b$oc2 is o"ten used to rite c$ean<upcode.
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try<catc#<@na$$y &'amp$e
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!ecap
• *$gorit#ms – -$oc#art= decision tab$e
• C; Programming Language –
Mariab$es= constants= data types= arrays=operators= met#ods
• Decision Structures – i"= i"<e$se= sitc#
• !epetition Structures – #i$e= do<#i$e= "or= "oreac#= recursion
• &'ception and$ing – try<catc#= try<@na$$y= try<catc#
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