chuong 08 - mot so van de khac.pdf

7/21/2019 Chuong 08 - Mot so van de khac.pdf

1/64

CHNG 8.MT S VN KHC

ThS. Trn Anh Dng


2/64

Khun mu (Template)

05/12/2014 Lp trnh hng i tng 2

Lp trnh tng qut1

Lp trnh tng qut trong C++2

C++ template3

Khun mu hm4

Khun mu lp5

5


3/64

Gii thiu

V dxt hm hon vnhsau:

Nu ta mun thc hin cng vic tng t chomtkiudliukhc, chnghnfloat?


voidswap ( int&a, int&b){

inttemp;

temp = a; a = b; b = temp;

}


4/64

Gii thiu

V dkhc: Ta nhnghamt lpbiudincu

trc ngnxpcho kiuint


classStack {

public:

Stack();

~Stack();

voidpush ( constint&i);

voidpop ( int&i);

boolisEmpty() const;

//...

};


5/64

Gii thiu

Khai bo v nhnghacaStack ph thuc ti

mtmcno vo kiudliuint.

Mtsphngthclytham sv trvkiuint

Nu ta mun tongnxpcho mtkiud liukhc

th sao?

Ta c nn nhngha lihon ton lpStack (ktqu

stora nhiulpchnghnIntStack, FloatStack,)

hay khng?



6/64

Lp trnh tng qut

Lptrnh tngqut l phngphp lptrnh c

lpvichi titbiudindliu.

T tng l ta nh ngha mt khi nim khng ph

thucmtbiudinc thno, v sau mich ra

kiudliuthch hplm tham s.

Nhvytrong mtstrnghp,achi titv

kiudliuvo trong nhnghahm hoclpl

iukhng c li.



7/64

Lp trnh tng qut trong C

Sdngtrnh tinxl caC

Trnh tinxl thchinthay thtext trckhi dch

Do ,ta c thdng #define chra kiudliuv

thay itichkhi cn.


#define TYPE int

voidswap(TYPE& a, TYPE& b) {

TYPEtemp;


}


8/64

Lp trnh tng qut trong C

Sdngtrnh tinxl caC

Nhm chn v dli

Chcho php ngmtnhngha trong mtchng

trnh.


#define TYPE int

voidswap(TYPE& a, TYPE& b) {

TYPEtemp;

temp = a; a = b; b = temp;}


9/64

C++ Template

Template (khun mu)l mtcchthay thcho

php tocc cutrc m khng phichr kiu

dliungay tu.

Tkha template cdng trong C++ bo

cho trnh bin dchbitrngonm theo sau sthao tc mt hoc nhiu kiu d liu cha xc

nh



10/64

C++ Template

T kha template c theo sau bi mt cp

ngocnhncha tn cacc kiud liu ty

ccung cp.

template

template

Mt lnh template ch c hiu qu i vi khai

bo ngay sau n



11/64

C++ Template

Hai loikhun mucbn:

Function templatekhun muhm cho php

nh ngha cc hm tng qut dng n cc

kiudliuty .

Class template khun mu lp cho php

nh ngha cc lp tng qut dng n cckiudliuty .



12/64

Khun mu hm

Khun mu hm l dng khun mu n gin

nht cho php ta nhngha cc hm dng n

cc kiudliuty .

V d sau nh ngha hm swap() bng khun

mu:


template

voidswap(T & a, T & b) {T temp;


}


13/64

Khun mu hm

Thc cht, khi s dng template, ta nh

nghamt tpv hncc hm chngnhau vi

tn swap()

gi mt trong cc phin bn ny, ta ch cn

gin vikiudliutngng


intx = 1, y = 2;floata = 1.1, b = 2.2;

swap(x, y); //Gi hm swap() vi kiu int

swap(a, b); //Gi hm swap() vi kiu float


14/64

Khun mu hm

Chuyng xyra khi ta bin dchm?

Trcht,sthay th"T" trong khai bo/nh

ngha hm swap() khng phi thay th text

n gin v cng khng c thc hin bi

trnh tinxl.

Vicchuynphin bnmucaswap() thnhcc ci t c th cho int v float c thc

hinbitrnh bin dch.



15/64

Khun mu hm

Hy xem xt hot ng ca trnh bin dch khi

gpligiswap() thnht(vihai tham sint)

Trcht,trnh bin dchtm xem c mthm

swap() c khai bo vi 2 tham s kiu int

hay khng? khng tm thynhng tm thy

mttemplate c thdng c.



16/64

Khun mu hm

Tip theo, n xem xt khai bo ca template

swap()xem c thkhpcviligihm

hay khng?

Ligihm cung cphai tham sthuccng mtkiu

dliu(int)

Trnh bin dchthytemplate chra hai tham sthuc

cng kiuT, nn n ktlunrngT phil kiuint

Do ,trnh bin dchktlunrngtemplate khpvi

ligihm



17/64

Khun mu hm

Khi xc nh c template khp vi ligi

hm, trnh bin dch kim tra xem c mt

phin bn ca swap() vi hai tham s kiu int

csinh ra ttemplate hay cha?

Nu c, ligic lin kt (bind) viphin bn

csinh ra

Nu khng, trnh bin dch s sinh mt ci t ca

swap() lyhai tham skiuint - v lin ktligihm

viphin bnvasinh.



18/64

Khun mu hm

Nh vy, n cui quy trnh bin dch on m

trong v d,sc hai phin bncaswap() c

tovicc ligihm ca ta c lin ktvi

phin bnthch hp.

Chi ph v thi gian bin dch i vi vic s dng

template?

Chi ph v khng gian lin quan n mi ci tca

swap() ctotrong khi bin dch?



19/64

Khun mu lp

Tngtvikhun muhm vitham sthuc

cc kiu ty , ta cng c thnhngha khun

mu lp (class template) s dng cc th hin

camthocnhiukiudliuty .

Vickhai bo mtkhun mulpcngtngt

vikhun muhm


template classClassName {

definition

}


20/64

Khun mu lp

V d: ta stomtcutrc cpigimtcp

gi trthuckiuty .

Trcht,xt khai bo Pair cho mtcpgi tr

kiuint nhsau:


struct Pair {

intfirst;intsecond;

};


21/64

Khun mu lp

Ta c th sa khai bo trn thnh mt khun

mulykiuty :

Tuy nhin hai thnh vin first v second phi

thuccng kiu


template

structPair {

T first;

T second;

};


22/64

Khun mu lp

Ta c thcho php hai thnh vin nhncc kiu

dliukhc nhau:


template

structPair {

T first;

U second;

};


23/64

Khun mu lp

to cc th hin ca template Pair, ta phi

dng k hiu cp ngoc nhn (khc vi khun

muhm)


Pair p; // Khng c

Pair q; // Creates a pair of ints

Pair r; // Creates a pair with an int and

a float


24/64

Khun mu lp

Khi thit k khun mu (cho lp hoc hm),

thng thng, ta nn to mt phin bn c th

trc, sau michuynn thnh mttemplate.

V d,ta sbtubngvicci thon chnh

Stack cho snguyn.

iu cho php pht hin cc vnvkhinim trc khi chuyn thnh phin bn cho s

dngtngqut.



25/64

Khun mu lp V d

V d: Xt lpStack visnguyn


class Stack {

private:

static const int max = 10;

intcontents[max], current;

public:

Stack(); ~Stack();

voidpush(const int& i);

voidpop(int& i);


boolisFull() const;

};


26/64

Khun mu lp V d


Stack::Stack() { this->current = 0; }

Stack::~Stack() {}

voidStack::push(const int& i) {

if (this->current < this->max) this->contents[this->current++] = i;

}

voidStack::pop(int& i) {

if(this->current > 0) i = this->contents[--this->current];

}

boolStack::isEmpty() const{ return(this->current == 0;) }

boolStack::isFull() const{

return(this->current == this->max);

}


27/64


28/64

Khun mu lp V d


template

Stack::Stack() {

this->current = 0;

}

template

Stack::~Stack() { }

template

voidStack::push(constT& i)

{

if(this->current < this->max)

this->contents[this->current++] = i;

}

Miphngthccnmtlnhtemplate ttrc

Mikhi dng ton tphmvi, cn mt k hiu ngocnhnkm theo tn kiu.Ta angnhnghamtlpStack, ch khng

phinhnghalpStack


29/64

Khun mu lp V d


template

voidStack::pop(T& i) {

if(this->current > 0)

i = this->contents[--this->current];

}

template

boolStack::isEmpty() const{

return(this->current == 0;)

}

template

boolStack::isFull() const{

return(this->current == this->max);

}

Thay th kiu ca i tng

c lu trong ngn xp (trcl int) bngkiuty T


30/64

Khun mu lp V d


intx = 5,

charc = 'a',

Stack s

Stack t

s.push(x);

t.push(c);s.pop(y);

t.pop(d);


31/64

Cc tham s khun mu khc

Phn trc chng ta ch mi ni n cc lnh

template vitham sthuc"kiu"class.

Tuy nhin, chng ta c thsdngcc tham s

kiuv tham sbiuthctrong khun mulp

template

Stack s;



32/64


Trong ci tStack, ta c mthngmax quy nh

s lng ti a cc i tng m ngn xp c

thchami thhins c cng kch thc

ivimikiucaitngccha.

Ta khng munmiStack uc kch thc ti

a nh nhau C th thm mt tham s vo

lnh template ch ra mt s int (gi tr ny s

cdng xc nhgi trcho max)


template


33/64



templateclassStack {

public:

Stack();

~Stack();voidpush(const T& i);

voidpop(T& i);


boolisFull() const;

private:staticconstintmax = M;

Tcontents[max];

intcurrent;

};

Khai bo tham s mi

Sdngtham smi xc nh gi trmax ca mt lpthucmtkiuno


34/64



template

Stack::Stack() { this->current = 0; }

template

Stack::~Stack() {}

template

void Stack::push(constT& i) {

if (this->current max)

this->contents[this->current++] = i;

}

Sa cc lnhtemplate

Sa tn lpdng cho cc

ton tphmvi


35/64


Gita c thtocc thhincacc lpStack

vicc kiudliuv kch thcadng


Stack s;Stack t;

Stack u;


36/64

Ngoi l (Exception)


Gii thiu1

Cch x l li truyn thng2

Ngoi l trong C++3

Kim sot ngoi l4

Lp ngoi l exception55


37/64

Gii thiu

Mi on chng trnh u tim n kh nng

sinh li

Lichquan: do lptrnh sai

Likhch quan: do dliu,do trngthi cahthng

Lic 2 loi?

Ngoi l (Exception): cc trnghphotngkhng bnh thng



38/64

Cch x l li truyn thng

Ci tm xl tinipht sinh ra li

Lm cho chngtrnh trnn kh hiu

Khng philc no cngythng tin xl

Khng nhtthitphixl

Truyntrngthi ln mctrn

Thng qua tham s, gi tr tr li hoc bin tng th

(flag)

Dnhm

Kh hiu



39/64



intdevide(intnum, intdenom, int& error){

if(0 != denom){

error = 0;

return num/denom;

} else{

error = 1;

return0;}

}


40/64


Kh kimsot chtcc trnghp

Lishc

Libnh

Lptrnh vin thngqun khng xl li

Bnchtcon ngi

Thiukinh nghim,ctnh bqua



41/64

C++ Exception

ExceptionNgoill cchthng bo v xl

ligiiquytccc vngpphitrn.

Tch cphnxl lira khiphnthutton

chnh.

Cho php mt hm c th thng bo v nhiu

loingoilC ch ngoi l mm do hn kiu x l li

truynthng


C


42/64

Cc kiu ngoi l

Mtngoi l l mti tngcha thng tin v

mt li v cdng truyn thng tin ti

cpthcthi cao hn.

Ngoilc ththuckiudliubtkcaC++

C sn,chnghnint, char*,

Hockiungidng tnhngha(thngdng)

Cc lpngoiltrong thvin


C h i l


43/64

C ch ngoi l

Qu trnh truyn ngoi l t ng cnh thc thi

hin hnh ti mc thc thi cao hn gi l nm

mtngoil(throw an exception).

V tr trong m cahm ningoi lcnm c

gil imnm (throw point)

Khi mtngcnhthcthi tipnhnv truy nhp

mtngoi l,n c coi l btngoi l (catch

the exception)


C h i l


44/64

C ch ngoi l

Quy trnh gi hm v tr v trong trng hp

bnh thng:


voidmain() {

intx, y;

cout > x >> y;

cout


45/64

C ch ngoi l

Quy trnh nm v btngoil:


throws

exception

catches

exeption

C h l i l


46/64

C php x l ngoi l

C ch x l ngoi l ca C++ c 3 tnh nng

chnh:

Khnng to v nm ngoi l (sdng tkho

throw)

Khnngbt v giiquytngoi l (sdng t

kho catch)

Khnngtch logic x l ngoi ltrong mthm

ra khiphncn licahm (sdngtkho try)


N i l th


47/64

Nm ngoi l throw

nm mtngoil, ta dng tkha throw, km

theo itngm ta nhnm.

Ta c thdng mithlm ngoil,kcgi tr

thuckiuc sn.


doubleMyDivide(doublenumerator, doubledenominator){

if(denominator == 0.0) {

throwstring(The denominator cannot be 0.);} else{

returnnumerator / denominator;

}

}

Ki t i l


48/64

Kim sot ngoi l

Khitrycatch dng :

Tch phngiiquytlira khiphnc thsinh li

Quy nh cc loingoi lcbt timc thc thi

hinhnh


try{

// Code that could generate an exception

}catch() {

// Code that resolves an exception of that type

};

Ki t i l


49/64

Kim sot ngoi l

C thc nhiukhicatch, mikhicham

giiquytmtloingoilcth:


try{// Code that could generate an exception

}catch() {

// Code that resolves a type1 exception}catch() {

// Code that resolves a type2 exception}catch() {

// Code that resolves a typeN exception};

Ki t i l V d


50/64

Kim sot ngoi l V d


voidmain() {intx, y;

doubleresult;

cout > x >> y;try{

result = MyDivide(x, y);

cout


51/64

S kh i l


52/64

So khp ngoi l

Khi mtngoilcnm ttrong mtkhitry,

hthngxl ngoilskimtra cc kiuc

litk trong khicatch theo thtlitk:

Khi tm thykiukhp,ngoilccoi l

cgiiquyt,khng cntiptctm kim.

Nukhng tm thy,mcthcthi hinhnh b

kt thc, ngoi l c chuyn ln mc cao

hn.


S kh i l


53/64

So khp ngoi l

Khi tm cc kiud liukhpvingoi l, trnh

bin dchni chung skhng thchinikiu

tng.

Nu mt ngoi l kiu float c nm, n s khng

khpvimtkhicatch cho ngoilkiuint

Mtitnghoctham chiukiudnxuts

khpvimtlnhcatch dnh cho kiucs

Numtngoi lkiuCarcnm, n skhpvi

mtkhicatch cho ngoilkiuMotorVehicle


S kh i l


54/64

So khp ngoi l

Vngpphi?

Mi ngoi l l i tng c sinh t cy

MotorVehicle s khp lnh catch u tin (cc

lnhcn liskhng bao gichy)


try{//

}

catch(MotorVehicle& mv) {}

catch(Car& c) {}catch(Truck& t) {};

So khp ngoi l


55/64

So khp ngoi l

Nu mun bt cc ngoi l dn xut tch khi

ngoi l c s, ta phi xp lnh catch cho lp

dnxutln trc:


try{

//

}

catch(Car& c) {}catch(Truck& t) {}

catch(MotorVehicle& mv) {};

So khp ngoi l


56/64

So khp ngoi l

Nu ta mun bt tt c cc ngoi l c nm

(kccc ngoilta khng thgiiquyt)?

c mt lnh catch btcmingoi l, ta

tduba chmbn trong lnhcatch.

Ch nn s dng n cho lnh catch cui cng

trong mtkhitry-catch.


catch(){

//

};

Lp exception


57/64

Lp exception

tch hphnnacc ngoi lvo ngn ngC++, lp exception c a vo th vin

chun.

Sdng#include v namespace std

Sdngthvinny, ta c thnm cc thhin

caexception hoctocc lpdnxutt.

Lpexception c mthm owhat(), c thnh

nghaliwhat() trvmtxu k t.


Lp exception


58/64

Lp exception

Mtslpngoilchunkhc cdnxuttlpcsexception.

File header (cng thuc th vin

chunC++) chamtslpngoildnxutt

exception. Trong c hai lpquan trngc

dnxuttrctiptexception:

runtime_error

logic_error


Lp exception


59/64

Lp exception

runtime_error: Cc li trong thi gian chy (ccli l kt qu ca cc tnh hung khng mong

i,chnghn: htbnh)

logic_error: Cc li trong logic chng trnh

(chnghntruyntham skhng hpl)

Thng thng,ta sdng cc lpny (hoccc

lp dn xut ca chng) thay v dng trc tip

exception


Lp exception


60/64

Lp exception

runtime_errorc cc lpdnxutsau:range_error iukinsau (post-condition) bvi phm

overflow_error xyra trn shc

bad_alloc khng thcppht bnh

logic_errorc cc lpdnxutsau:

domain_error iu kin trc (pre-condition) b viphm

invalid_argument tham s khng hp l c truyncho hm

length_errortoitnglnhndi cho php

out_of_rangetham sngoi khong05/12/2014 Lp trnh hng i tng 60

Lp exception


61/64

Lp exception

Ta c thvitlihm MyDivide() sdngccngoilchuntngngnhsau:


doubleMyDivide(doublenumerator, doubledenominator)

{if(denominator == 0.0) {

throwinvalid_argument(The denominator cannotbe 0.);

} else{returnnumerator / denominator;

}

}

Lp exception


62/64

Lp exception


voidmain() {intx, y;doubleresult;

do{

cout > x >> y;

try{result = MyDivide(x, y);

cout


63/64

u im exception trong C++

DsdngDdng chuyniukhinnnic khnngxl

ngoil

C thnmnhiuloingoil

Tch xl ngoilkhithutton

Tch m xl

Sdngc php khcKhng bst ngoil(nmtng)

Chngtrnh dchn,an ton hn


Q & A


64/64

Q & A

chuong 08 - mot so van de khac.pdf

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