Chuong 01 - Cac dac diem moi cua C++

CHNG 1. CC C IM MI CA C++

ThS. Trn Anh Dng

Ni dung

14/09/2014 Lp trnh hng i tng 2

Mt s lu 1

Ngn ng C++ 2

Tham s mc nhin 3

Ti nh ngha hm 4

Truyn tham s 5 5

Hm ni tuyn 6

Phong cch lp trnh

Nhng lu v phong cch lp trnh:

t tn (bin, hm,)

Tab

Khai bo prototype

{}


Bi tp C

Nhp bn s nguyn v xut cc gi tr va

nhp

C bao nhiu cch gii quyt?


Bi tp C Gii

1. Dng 4 bin cch di nht, c bn nht

2. Dng mng khai bo bin gn hn, 1

ln thay cho nhiu ln

3. Dng mng v vng lp do while vit

code nhp gn hn, vit 1 ln thay cho

nhiu ln

4. Dng mng v vng lp for vit code

gn hn, for vit gn hn vng while 14/09/2014 Lp trnh hng i tng 5

Bi tp C Gii

5. Dng mng, vng lp for gp vit code

gn hn, nhng khng tch ring c 2

phn nhp xut

6. Dng hm tch ring phn nhp xut

code c th ti s dng nhiu ln

7. Dng file nhp xut t file thay cho vic

nhp bng bn phm v xut ra mn hnh


Bi tp C Gii

Cch 1: Dng 4 bin


void main(){

int a1, a2, a3, a4;

printf("\nNhap a1 = ");

scanf("%d", &a1);


scanf("%d", &a2);


scanf("%d", &a3);


scanf("%d", &a4);

printf("\nBan vua nhap 4 so: %d %d %d %d\n", a1, a2, a3, a4);

}

Bi tp C Gii

Cch 2: Dng mng


void main(){

int a[4];


scanf("%d", &a[0]);


scanf("%d", &a[1]);


scanf("%d", &a[2]);


scanf("%d", &a[3]);

printf("\nBan nhap 4 so:%d %d %d %d\n", a[0], a[1], a[2], a[3]);

}

Bi tp C Gii

Cch 3: Dng

mng v vng

lp while


void main(){

int a[4], i;

i = 0;

do{

printf("\nNhap a%d = ", i);

scanf("%d", &a[i]);

i++;

}while(i

Bi tp C Gii

Cch 4: Dng mng v vng lp for


void main()

{

int a[4], i;

for (i=0; i

Bi tp C Gii

Cch 5: Dng mng v vng lp for gp


void main()

{

int a[4], i;

for (i=0; i

Bi tp C Gii

Cch 6: Dng hm


Bi tp C Gii

Cch 7: Dng file


Lch s ngn ng lp trnh


Lch s ca C++

M rng ca C

u thp nin 1980: Bjarne Stroustrup

(Bell Laboratories)

Cung cp kh nng lp trnh hng i

tng

Ngn ng lai


Mi trng ca C++

Bin dch v thc thi chng trnh C++: Edit

Preprocess

Compile

Link

Load

Execute


Loader

Primary

Memory

Program is created in

the editor and stored

on disk.

Preprocessor program

processes the code.

Loader puts program

in memory.

CPU takes each

instruction and

executes it, possibly

storing new data

values as the program

executes.

Compiler

Compiler creates

object code and stores

it on disk.

Linker links the object

code with the libraries,

creates a.out and

stores it on disk

Editor

Preprocessor

Linker

CPU

Primary

Memory

.

.

.

.

.

.

.

.

.

.

.

.

Disk

Disk

Disk

Disk

Disk

Khc bit i vi C

Ch thch

Cc kiu d liu

Kim tra kiu, i kiu

Phm vi v khai bo

Khng gian tn

Hng

Qun l b nh

Tham chiu


C++

C

Khc bit i vi C

Phm vi v khai bo:

Khng ging nh C, chng ta c th khai bo mt

bin ti mt v tr bt k trong chng trnh.

Mt bin ch c tm tc dng trong khi lnh n

c khai bo.

Do , C++ cung cp ton t nh phm vi (::)

xc nh r bin no c s dng khi xy ra tnh

trng nh ngha chng mt tn bin trong mt

khi lnh con.


Ton t phm vi

Ton t phm vi (::)

Thng c dng truy cp cc bin ton

cc trong trng hp c bin cc b trng tn

V d:

y = ::x + 3;


Ton t phm vi


1 // Using the unary scope resolution operator.

2 #include

3 #include

4 using namespace std;

5

6 // define global constant PI

7 const double PI = 3.14159265358979;

8 int main()

9 {

10 //define local constant PI

11 const float PI = static_cast< float >( ::PI );

Access the global PI with

::PI.

Cast the global PI to a

float for the local PI.

This example will show

the difference between

float and double.

Ton t phm vi


12 // display values of local and global PI constants

13 cout

Nhp xut vi C++

cin

Lung nhp chun

cout

Lung xut chun

cerr

Lung thng bo li chun


Nhp xut vi C++

cin and cout (and #include ):

cout > name;

cout

V d 1


1 // Fig. 1.2: fig01_02.cpp

2 // A first program in C++.

3 #include


5 // function main begins program execution

6 int main()

7 {

8 cout

V d 2


1 #include


3 // function main begins program execution

4 int main(){

5 int integer1; // first number to be input by user

6 int integer2; // second number to be input by user

7 int sum; // variable in which sum will be stored

8 cout > integer1; // read an integer

10 cout > integer2; // read an integer

12 sum = integer1 + integer2; // assign result to sum

13 cout

V d 3


#include

using namespace std;

void main() {

int n;

double d;

char s[100];

cout > n >> d >> s;

cout

Cc kiu d liu ca C++


structured

array struct union class

address

pointer reference

simple

integral enum floating

float double long double

char short int long bool

Tham s mc nhin

V d 1: Hm th hin mt ca s thng bo

trong Visual C++


Tham s mc nhin

V d 2:


Tham s mc nhin

Mc ch:

Gn cc gi tr mc nhin cho cc tham s ca hm.

Khai bo tham s mc nhin:

Tt c cc tham s mc nhin u phi cui hm.

Ch cn a vo khai bo, khng cn trong nh ngha.

Gi hm c tham s mc nhin:

Nu cung cp tham s dng tham s truyn vo.

Nu khng tham s dng tham s mc nhin.


Ti nh ngha hm

Funtions overloading

C++ cho php nh ngha cc hm trng

tn.


int abs(int i);

long labs(long l);

double fabs(double d);

int abs(int i);

long abs(long l);

double abs(double d);

Ti nh ngha hm

Qui tc ti nh ngha:

Cc hm trng tn phi khc nhau v tham s:

S lng, th t, kiu

Qui tc gi hm?

Tm hm c kiu tham s ph hp

Dng php p kiu t ng

Tm hm gn ng (ph hp) nht


Ti nh ngha hm

V d 1:


Ti nh ngha hm

V d 2:


Ton t qun l b nh ng

Ton t cp pht b nh ng new

int *x;

x = new int; //x = (int*)malloc(sizeof(int));

char *y;

y = new char[100]; //y = (char*)malloc(100);

Ton t gii phng vng nh ng delete

delete x; // free(x);

delete y; // free(y);


Truyn tham s

Truyn theo gi tr (tham tr)

Gi tr tham s khi ra khi hm s khng thay

i.

Truyn theo a ch (tham chiu)

Gi tr tham s khi ra khi hm c th thay i.


Tham chiu

Tham chiu l a ch vng nh c cp

pht cho mt bin.

K hiu & t trc bin hoc hm xc

nh tham chiu ca chng

V d 1:

int x = 10, *px = &x, &y = x;

*px = 20;

y = 30;


Tham chiu

V d 2:

int arrget(int *a, int i) { return a[i]; }

arrget(a, 1) = 1; // a[1] = 1;

cin >> arrget(a,1); // cin >> a[1];

V d 3:

void swap1(int x, int y) { int t = x; x = y; y = t; }

void swap2(int *x, int *y) { int *t = x; x = y; y = t; }

void swap3(int &x, int &y) { int t = x; x = y; y = t; }


Tham chiu


1 // Comparing pass-by-value and pass-by-reference

2 // with references.

3 #include


5

6 int squareByValue( int ); // function prototype

7 void squareByReference( int & ); // function prototype

8 int main(){

9 int x = 2, z = 4;

10 // demonstrate squareByValue

11 cout

Tham chiu


15 // demonstrate squareByReference

16 cout

Tham chiu


1 // References must be initialized.

2 #include

3 using std::cout;

4 using std::endl;

5 int main(){

6 int x = 3;

7

8 int &y = x;

9 cout

Tham chiu


1 #include


3 int main(){

4 int x = 3;

5 int &y;

6 cout

Hm Inline

Hm inline hay cn gi l hm ni tuyn.

S dng t kha inline

Yu cu trnh bin dch copy code vo trong

chng trnh thay v thc hin li gi hm:

Gim thi gian thc thi chng trnh

Tng kch thc ca m lnh thc thi

Ch nn nh ngha inline khi hm c kch

thc nh


Hm Inline

V d:


Lp trnh Hng i tng 45

Tm li sai cho cc khai bo prototype hm di y (cc hm ny trong cng mt chng trnh):

int func1 (int);

float func1 (int);

int func1 (float);

void func1 (int = 0, int);

void func2 (int, int = 0);

void func2 (int);

void func2 (float);

Bi tp 1


Cho bit kt xut ca chng trnh sau: void func (int i, int j = 0 ){ cout


a. Vit chng trnh nhp vo mt phn s,

rt gn phn s v xut kt qu.

b. Vit chng trnh nhp vo hai phn s,

tm phn s ln nht v xut kt qu.

c. Vit chng trnh nhp vo hai phn s.

Tnh tng, hiu, tch, thng gia chng

v xut kt qu.

Bi tp 3


a. Vit chng trnh nhp vo mt ngy.

Tm ngy k tip v xut kt qu.

b. Vit chng trnh nhp h tn, im ton,

im vn ca mt hc sinh. Tnh im

trung bnh v xut kt qu.

Bi tp 4

Bi tp 5

Cho mt danh sch lu thng tin ca cc nhn vin trong mt cng ty, thng tin gm:

- M nhn vin (chui, ti a l 8 k t)

- H v tn (chui, ti a l 20 k t)

- Phng ban (chui, ti a 10 k t)

- Lng c bn (s nguyn)

- Thng (s nguyn)

- Thc lnh (s nguyn, trong thc lnh = lng c bn + thng )

Hy thc hin cc cng vic sau:

a.Tnh tng thc lnh thng ca tt c nhn vin trong cng ty.

b.In danh sch nhng nhn vin c mc lng c bn thp nht.

c.m s lng nhn vin c mc thng >= 1200000.

d.In danh sch cc nhn vin tng dn theo phng ban, nu phng ban trng nhau th

gim dn theo m nhn vin.


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Chuong 01 - Cac dac diem moi cua C++