advanced programming slides preliminary

118.07.2012 Janne Mntykoski 1

Advanced programming

Janne [email protected]

Room B501


Course focus

C++ programming Advanced C programming Focus is on programming a microcontroller

(mbed, LPC1768)

2Main contents C++- Class - objects- Derived class base class inheritance- Polymorfism easier function naming C and C++- Strings- Pointers- Structure



WWW-sites and books

Wikipedia: C++ ja Olio-ohjelmointi Mureakuha: cpp.mureakuha.com Rintala ja Jokinen: Olioiden ohjelmointi C++:lla,

Talentum Vaatii C-kielen osaamisen pohjalle Pivi Hietanen: C++ ja olio-ohjelmointi - Kattava

C++ teos Overland: C++ Without Fear 2/E

Osa kalvojen esimerkeist suoraan Wikipediasta tai Mureakuhasta


Free programming environments

Code:blocks supports both C and C++ -languageswww.codeblocks.org

Dev-C++ supports both C and C++ -languageswww.bloodshed.net


Embedded programming environment

Online C++ compiler for mbed module, ARM Cortex-M3 LPC1768 microcontroller, Cortex-M0 module also available

A lot of libraries for devices for mbedwww.mbed.org


Why C++?

C++ - language is very popular It supports modern coding technics like

object oriented programming SystemC hardware description language

is based on C++ The powerful mbed module supports C++,

ARM Cortex-M3


Introduction to C++ Development sterted in 1979 Main designer Bjarne Stroustrup Expands the C language with modern

coding technics like object oriented programming

Object oriented programming is very useful in big coding projects

First ANSI standard in 1998, ANSI C++, ISO

5C++ programming


C++ source files, extension .cpp C++ header files, extension .h or .hpp

Precompiler, #-directives

Compiler, creates .obj files

Linker, combines .obj files and adds startup code

Executable program, extension .exe or .bin


C and C++ comparisonC style#include main() {

printf ("Hello World!\n");}C++#include int main() {

std::cout

6#include using namespace std;void main(void){

char c;cout


Class Circle.hpp file#include using namespace std;const double pi = 3.141; class Ball{private :

// Place for variables and functionspublic:

float ray_v;float GiveSurfaceArea(){ return pi*ray*ray; };float GiveCF(){ return 2.0*pi*ray; };

};int main(){

Ball ball1;

ball1.ray_v = 3;cout


Benefits from object oriented programming

The code has been divided into clear sub-programs with objects:

- Easier to design- Easier to understand- Easier to reuse- Easier to modify

C code C++ code

Ways to manage the code

Use state machines to organise the code Use objects to combine variables and

functions into understandable sub-programs

When to use objects?: Definitely when the code size starts to increase



Object oriented programming Three new things:

- encapsulation -> objects and classes (type of object)- inheritance -> class reuse- polymorfism -> function name overloading

By encapsulation we are hiding part of the complexity of the code -> object interface is simpler than the object

Inheritance means less coding and more code reuse Polymorphism simplifies naming functions and their use


Class Ball.hpp fileconst double pi = 3.141; class Ball{protected :

float ray_v;// Place for Protected functions

public:// Place for Public variables, not recommendedBall();Ball(float ray);~Ball() {};void SetRay(float raysade);float GiveRay();float GiveSurfaceArea();float GiveVolume();

};

Constant PIBegin class declaration

Inheritable, Invisible to the outside

External interface

Class creatorsClass destructor

Declaration ofClass functions

ray_vGiveSurface

Area

GiveVolume

SetRay

GiveRay

New Ray value

The Ray value

Surface AreaVolume

Public inteface

Protected variable

End class declaration

Class is the type of the object

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#include #include Ball.hpp"Ball::Ball();

Ball::SetRay(1.0);};Ball::Ball(float ray){

Ball::SetRay(ray);}void Ball::SetRay(float ray){

ray_m = ray;}float Ball::GiveRay(){

return ray_v;}float Ball::GiveSurfaceArea(){

return 4*pi*ray*ray;}float Ball::GiveVolume(){

return 4.0/3.0*pi*ray*ray*ray;}


Class Ball.cpp file

DefinitionsofClass functions

Class constructor, no parameters,default ray=1.0

Class constructor with parameter

ray_vSetRayNew Ray value

ray_v GiveRay The Ray value

ray_v GiveSurfaceArea

Surface Area

ray_v GiveVolume Volume

Notice

#include #include Ball.hpp"

using namespace std;

int main(){

Ball ball1(2);Ball ball2;

cout

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Class constructors and destructor

Constructor is called when object is created

Constructor Object creation Initialization

Ball(); Ball ball2; Default value(s)

Ball(float ray); Ball ball1(2); Parameter value(s)

Destructor Action

~Ball() {}; Free any reserved dynamicmemory

Destructor is called when object is deleted or in the end of the program

Complex objects

Class constants: the same for class objects

Class wide variable: the same for class objects

Object copying possible Object pointers


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Program pause

Program will wait for ENTER to be pressed


C style (DOS command) C++

system(PAUSE); cin.get();#include

Int main(void) {printf ("Hello!\n");system(PAUSE);return 0;

}

#include using namespace std;int main() {

cout

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StringsC C++

#include #include

int main(void) {char str1[30] = Hi!, str2[30];

strcpy(str2, str1);if (strcmp(str1, str2) == 0)

printf(They are equal\n);

printf(Length: %d, strlen(str2););

return 0;}

#include #include using namespace std;int main () {

string str1 = Hi!, str2;

str2 = str1;if (str1 == str2)

cout or equal to"

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Inheritance example, ColoredBall

Inheritance is an easy way to reuse code ColoredBall is called derived class19.07.2012 Janne Mntykoski 27

ray

GiveSurfaceArea

GiveVolume

SetRay

GiveRay

New Ray value

The Ray value

Surface Area

Volume

variables

Functions

Object interface

SetColor GiveColorcolorNew Color value

The Color value

Inherited,Base class Ball


Derived class ColoredBall.hpp file#include Ball.hpp"

class ColoredBall : public Ball{private :

int color_v;// Private functions

public:ColoredBall();ColoredBall(float ray, int color);~ ColoredBall() {};void SetColor(int color);int GiveColor(void);

};

ray_vGiveSurface

Area

GiveVolume

SetRay

GiveRay

New Ray valueThe Ray value

Surface Area

Volume

Public inteface

Private variable

color_v

SetColor

GiveColor

New Color valueThe Color value

Base class Ball

Inherit class Ball

Not inheritable, Invisible to the outside

External interfaceClass creators

Class destructorDeclaration ofClass functions

class Ball

15


Derived class ColoredBall.cpp file#include #include ColoredBall.hpp"

ColoredBall () {ColoredBall::SetColor(1);

};

ColoredBall::ColoredBall (float ray, int color){

Ball::SetRay(ray);ColoredBall::SetColor(color);

}

void ColoredBall::SetColor(int color){

color_v = color;}

int ColoredBall::GiveColor(void){

return color_v;}

Definitions of Class functions

Class constructor, no parameters,default Color=1.0

Class constructor with parameters

color_vSetColorNew Color value

color_v GiveColor The Color value

Notice

Class ColoredBall

#include #include ColoredBall.hpp"using namespace std;int main(){

ColoredBall ball1(3.0,2);ColoredBall ball2;

cout

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Function overloading is polymorfismC C++

int abs(int); int abs(int);

long labs(long); long abs(long);

double fabs(double); double abs(double);

There has to difference in parameter types Return type difference is not enough Polymorfism (=many forms) -> same

function name, many different functions Operator overloading is also possible


Polymorfism example, function abs#include using namespace std;

Int abs( int n);double abs( double n );

int main( ){

cout

17


C and C++ comparisonC style

#include int main(void){

int i, j=1;printf(Give integer: );scanf(%d, &i);printf(i is %d, j is %d\n, i. j);

}

C++#include using namespace std;int main(){

int i;cout

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#include using namespace std;void funktio(int &intM, float &intM);int main(){

int intN = 5;float floatN = 6.12;

cout

19

Advanced C programming


String pointers#include

void main(void){

char stringC[11] = String";char *string_pointer;

string_pointer = stringC + 6;printf(stringC = %s, stringC + 6 = %s\n", stringC, string_pointer);printf(Member?(alkio) 6 of stringC = %c\n", *string_pointer);

stringC[3] = '\0printf(stringC = %s\n", stringC);

stringC = stringC + 1;

system(PAUSE);}


Pointer to a memory location which contains character(s)

Add 6*(size of character= 1 byte)

'\0'-characters is the end of stringTherefore here is Str printed

INCORRECT! stringC is constant

Array name=stringC=address of the member 0 of array

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Pointers#include int main(){

int i = 5;int *ptr;float array[2] = {3.14, 0.07};float *ptr2;

ptr = &i;printf(Value of i: %d, Value in address ptr: %d.\n", i, *ptr);printf(Address of i: %p, value of pointer ptr %p.\n", &i, ptr);

ptr2= array;printf(Address of member 0 of array: %p, ptr2: %p.\n", array, ptr2);printf(Value of member 0 of array: %f. ptr2[0]: %f.\n", *array, ptr2[0]);

ptr2 = ptr2 + 1; printf(Address of member 1 of array: %p, ptr2: %p.\n", array+1, ptr2);printf(Value of member 1 of array: %f. ptr2[0]: %f.\n", array[1], ptr2[0]);

}


Pointer to a memory location which contains an integer

Pointer to a memory location which contains a float

& is address operatori=*ptr, * is contents operator&i=ptr

The same addressi=*ptr, * is contents operator

*array=array[0]

Add size of float= 4 bytes

array[1]=ptr2[0]


Pointer calculations#include int main(){

int i = 5;int *ptr;int array[3] = {3, 2, 1};int *ptr2;

*ptr++(*ptr)++

x = *ptr;ptr++;

}

kasvattaa osoittimen arvoa kahdellakasvattaa osoittimen osoittaman muistipaikan sislt yhdell

sallitut operaatiot ovat +, ++, - ja

OR! x = *ptr++;

21

#include

struct personStruct {char name[30];int age;

};

int main(void){

struct personStruct person;int j;

printf(Give name: ");fgets(person.name, 30, stdin);printf(Give age: ");scanf("%d", &(person.age));

for (j=0; j < 30; j++)if (person.name[j] == '\n')

person.name[j] = '\0';}

Structure


Read into field name in structure person

Remove newline \n from the end of string

Read into field age in structure person

Structure type personType containsfields name and age

#include

typedef struct personStruct {char name[30];int age;

} personType;

int main(void){

personType persons[2] = {{"Untamo",1},{"Juusto", 0}};personType *personsPtr;

personsPtr = persons;

printf(Member 0: name: %s, age: %d\n", persons[0].name, persons[0].age);printf(Member 0: name: %s, age: %d\n", personsPtr->name, personsPtr->age);

personsPtr++;printf(Member 1: name: %s, age: %d\n", personsPtr[0].name, personsPtr[0].age);printf(Member 1: name: %s, age: %d\n", personsPtr->name, personsPtr->age);

}

Array of structures


InitializeStructure pointer

Move to the next structure

Could be omitted, default=size of initialization

Type definition

22

#include #include void main(){

char *words[3][2]= {{"sana","word"},{"peli","game"},{"talo","house"}};char word[30];int i;

printf(Give word: ");fgets(word, 30, stdin);for (i=0; i < 30; i++)

if (word[i] == '\n')word[i] = '\0';

for (i=0; i

23

?Output file


C C++#include ???

int main(){

FILE *outputfile;outputfile=fopen(output.txt,w); //a?if (outputfile == NULL) {

printf(File open failed!);return 2;

}

char stringC[80];

printf(Give string: ");fgets(stringC, 30, stdin);fputs(stringC, outputfile);fputs(Hi, outputfile);fclose(outputfile);

}

#include #include using namespace std;

int main(void){

ofstream outputfile(output.txt");if (!outputfile) {

cout

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Bit fields In struct ja union you can define the number of

bits used Field has to be of type int or unsigned struct bit_card {

unsigned nro:4; /* 4 bits */unsigned country:2; /* 2 bits */unsigned color:1; /* 1 bit */

};

#include

typedef enum {START, SUCCESS} state_t;Int main(){

int c;state_t current_state = START, next_state = START;

while(1) {switch(current_state){

case START :next_state = SUCCESS;break;

case SUCCESS :printf(Program terminated.\n"); getch(); return;

}current_state=next_state;

}}

Enumerated type


State variables

START=0, SUCCESS=1

State machine

STATE_START

STATE_SUCCESS

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Dynamic memory allocation

Memory is allocated and freed during run-time

Function malloc() reserves memory Function free() releases the reserved

memory They are in stdlib.h library

Other additions to C++


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Other additions to C++

Classes: (Simula67) Operator overloading

Others: Type bool. Has two values: false and true. Dynamic type conversions of the variables Inline functions Dynamic memory allocation (new, delete)


Advanced I/OC++ code#include main(){// muutetaan formaattiacout

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?Output format


C C++ Output

printf(%f\n,123.234567);printf(%s\n, "hello);

cout

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