Orientação a objetos

Transcrição

Programação orientada a objetos
com C / C++ em ambiente
multiplataforma
n
Parte 4 – Orientação a objetos (adendo)
– versão 6.1 de 10 de Julho de 2002
n
Por Sergio Barbosa Villas-Boas
– www.del.ufrj.br/~villas
– [email protected]
copyright ©
sbVB
sbVB
http://www.del.ufrj.br/~villas
cout e sobrecarga do insersor (<<)
#include <iostream.h>
void main()
{
// cout << "Hello ";
cout.operator<<("hello");
Hello Hello
i=4
// cout << "Hello" << endl;
(cout.operator<<("hello")).operator<<(endl);
int i = 4;
// cout << "i=" << i << endl;
((cout.operator<<("i=")).operator<<(i)).operator<<(endl);
}
copyright ©
sbVB
1
Sobrecarga do insersor (<<) e extrator (>>)
class myClass
{
public:
int m_i;
myClass(int i = 0) {m_i = i;} // construtor
friend ostream & operator <<(ostream & s, const myClass & z)
{
s << z.m_i; // s.operator<<(z.m_i);
return s;
}
friend istream & operator>>(istream & s, myClass & z)
{
s >> z.m_i; // s.operator>>(z.m_i);
return s;
}
};
Entre com
void main()
a=22
{
myClass a;
cout << "Entre com o dado:";
// cin >> a; não é
operator>>(cin, a);
o dado:22
"cin.operator>>(a);"
// cout << "a=" << a << endl;
copyright © sbVB
(operator<<(cout.operator<<("a="),
a)).operator<<(endl);
}
Escrevendo arquivo texto (1)
#include <fstream.h>
class myClass {
public:
int m_i[2];
friend ostream & operator << (ostream & s, const myClass & a) {
s << a.m_i[0] << endl << a.m_i[1]; // não incluir << endl
return s;
c:\xxx\fileout.dat
}
3.14↵
↵
};
void main() {
2.3456↵
↵
float pi=3.14;
12↵
↵
double d = 2.3456;
24↵
↵
myClass z;
z.m_i[0] = 12; z.m_i[1] = 24;
ofstream myFile;
const char* fname = "c:\\xxx\\fileout.dat";
myFile.open (fname);
if (!myFile)
cout << "File " << fname << " not open";
myFile << fname << endl;
myFile << pi << endl;
myFile << d << endl;
myFile << z << endl;
// myFile.close(); // not necessary,
//because
by destructor
copyright
© sbVBfile is closed
}
2
class myClass {
public:
int m_i[2];
return s;
}
};
void putToFileOrConsole(ostream & device,
float pi, double d, myClass z, const char *fname) {
c:\xxx\fileout.dat
device << fname << endl;
3.14↵
↵
device << pi << endl;
2.3456↵
↵
device << d << endl;
12↵
↵
device << z << endl;
24↵
↵
}
void main() {
float pi=3.14;
double d = 2.3456;
myClass z;
z.m_i[0] = 12;
z.m_i[1] = 24;
c:\>program↵
↵
ofstream myFile;
c:\xxx\fileout.dat
const char* fname = "c:/xxx/fileout.dat";
3.14
fname = "c:\\xxx\\fileout.dat";
2.3456
12
if (!myFile)
24
putToFileOrConsole(myFile, pi, d, z, fname);
c:\>
putToFileOrConsole(cout,
pi, d, z,
fname);
copyright © sbVB
}
Escrevendo arquivo texto (2)
#include "vblib.h"
class myClass {
public:
int m_i[2];
return s;
}
friend istream & operator >> (istream & s, myClass & a) {
s >> a.m_i[0] >> a.m_i[1];
return s;
}
c:\>program↵
↵
};
file=c:\xxx\fileout.dat
void main() {
pi=3.14
VBString str;
d=2.3456
float pi;
z=12
double d;
myClass z;
24
ifstream myFile;
c:\>
const char* fname = "c:\\xxx\\fileout.dat";
if (!myFile) {
cout << "File " << fname << " not open" << endl;
}
else {
myFile >> str >> pi >> d >> z;
cout << "file=" << str << endl
<< "pi=" << pi << endl
<< "d=" << d << endl
<< "z=" << z << endl;
copyright
© sbVB
}
}
Lendo arquivo texto
3
#include "vblib.h" // VBString
class person
{
// private attributes
VBString m_name;
VBString m_address;
VBString m_telephone;
float m_weight;
vários
atributos
na classe
Lendo/escrevendo
classe com
múltiplos atributos
public:
// public access methods
void setName(VBString name) { m_name = name; };
void setAddress(VBString address) { m_address = address; };
void setTelephone(VBString telephone) { m_telephone = telephone;};
void setWeight(float weight) { m_weight = weight;};
VBString getName() { return m_name; };
VBString getAddress() { return m_address;};
VBString getTelephone() { return m_telephone; };
float getWeight() { return m_weight;};
friend ostream & operator << (ostream & s, const person & obj) {
s << obj.m_name << endl
<< obj.m_address << endl
<< obj.m_telephone << endl
<< obj.m_weight; // não incluir << endl
return s;
}
friend istream & operator >> (istream & s, person & obj) {
s >> obj.m_name >> obj.m_address >> obj.m_telephone >> obj.m_weight;
VBString dummy;
s >> dummy; // read the <return> to synchronize file pointer
return s;
copyright
© sbVB
}
};
Lendo/escrevendo classe com múltiplos atributos (2)
void write() {
int times = 5;
person p;
VBString timesStr;
p.setName("test name");
p.setAddress("test address");
p.setTelephone("test telephone");
ofstream myFile;
const char* fname = "c:\\xxx\\fileout.txt";
if (!myFile) {
}
else {
for (int i=0 ; i < times ; i++) {
timesStr = "";
timesStr += i; // convert int to string
p.setName("test name " + timesStr);
p.setWeight(1.1+i);
myFile << p << endl; // write person object to file
}
}
}
copyright ©
sbVB
4
Lendo/escrevendo classe com múltiplos atributos (3)
void read()
{
person p;
ifstream myFile;
if (!myFile) {
}
else {
while (true) { // loop to read entire file
myFile >> p; // read person object from file
if (myFile.eof()) break;
cout << p << endl;
// write person object to console
}
}
}
copyright ©
sbVB
c:\>program↵
↵
test name 0
test address
test telephone
1.1
test name 1
test address
test telephone
2.1
test name 2
test address
test telephone
3.1
test name 3
test address
test telephone
4.1
test name 4
test address
test telephone
5.1
c:\>
Lendo/escrevendo classe com múltiplos
atributos (versão 2)
#include "vblib.h" // VBString
class Person
{
// private attributes
vários
VBString m_name;
atributos
VBString m_address;
VBString m_telephone;
na classe
float m_weight;
atributos
char m_token, m_token_substitute;
public:
auxiliares
Person() { m_token = '|'; m_token_substitute='_'; }
// public access methods
void setName(VBString name) { m_name = name; };
void setAddress(VBString address) { m_address = address; };
void setTelephone(VBString telephone) { m_telephone = telephone;};
void setWeight(float weight) { m_weight = weight;};
VBString getName() { return m_name; };
VBString getAddress() { return m_address;};
VBString getTelephone() { return m_telephone; };
float getWeight() { return m_weight;};
// (continua)
copyright ©
sbVB
5
Lendo/escrevendo classe com múltiplos
atributos (versão 2) (2)
// continuação do slide anterior
friend ostream & operator << (ostream & s, const Person & obj) {
char strToken[2], strTokenSubs[2];
strToken[0] = obj.m_token; strToken[1] = 0; // terminate string
strTokenSubs[0] = obj.m_token_substitute; strTokenSubs[1] = 0; // terminate string
VBString aux;
aux = obj.m_name; aux.strschg(strToken,strTokenSubs);
s << aux << obj.m_token;
aux = obj.m_address; aux.strschg(strToken,strTokenSubs);
aux = obj.m_telephone; aux.strschg(strToken,strTokenSubs);
s << obj.m_weight; // não incluir << endl
return s;
}
friend istream & operator >> (istream & s, Person & obj) {
VBString aux;
s >> aux; // read all attributes of object in one string
obj.m_name = aux.strtok(obj.m_token,0);
obj.m_address = aux.strtok(obj.m_token,1);
obj.m_telephone = aux.strtok(obj.m_token,2);
obj.m_weight = atof(aux.strtok(obj.m_token,3));
return s;
copyright © sbVB
}
};
Lendo/escrevendo classe com
múltiplos atributos (versão 2) (3)
n
Aspecto do arquivo de saída (e também
no console) usando a nova versão
(c:\xxx\fileout.txt)
test name 0|test address|test
copyright ©
sbVB
telephone|1.1↵
↵
telephone|2.1↵
↵
telephone|3.1↵
↵
telephone|4.1↵
↵
telephone|5.1↵
↵
6
Copiando arquivo texto para console
#include "vblib.h"
void main()
{
VBString line;
ifstream myFile;
myFile.open(fname);
if (!myFile)
{
}
while (true) // loop to read entire file
{
myFile >> line; // one line
cout << line << endl; // out to console
}
}
copyright ©
sbVB
c:\>program↵
↵
test name 0
test address
test telephone
1.1
test name 1
test address
test telephone
2.1
test name 2
test address
test telephone
3.1
test name 3
test address
test telephone
4.1
test name 4
test address
test telephone
5.1
c:\>
Copiando arquivo texto para console
(variante do programa usando string change feature)
#include "vblib.h"
void main()
{
VBString line;
ifstream myFile;
myFile.open(fname);
if (!myFile)
{
}
while (true) // loop to read entire file
{
myFile >> line; // one line
line.strschg("test","TEST");
line.strschg("name","Villas");
cout << line << endl; // out to console
}
copyright © sbVB
}
c:\>program↵
↵
TEST Villas 0
TEST address
TEST telephone
1.1
TEST Villas 1
TEST address
TEST telephone
2.1
TEST Villas 2
TEST address
TEST telephone
3.1
TEST Villas 3
TEST address
TEST telephone
4.1
TEST Villas 4
TEST address
TEST telephone
5.1
c:\>
7
Arquivo binário (Visual C++)
exemplo: copiando um arquivo binário
// Visual C++
#define TYPE unsigned char
void main()
{
TYPE buffer;
// to write, binary mode
ofstream writeFile;
ifstream readFile;
const char* fname = "c:\\xxx\\test.jpg";
const char* fname2 = "c:\\xxx\\test2.jpg";
readFile.open(fname, ios::binary);
if (!readFile)
writeFile.open(fname2, ios::binary);
if (!writeFile)
cout << "File " << fname2 << " not open";
while (true)
{
readFile.read((unsigned char*)&buffer, sizeof(TYPE));
if (readFile.eof()) break;
writeFile.write((unsigned char*)&buffer, sizeof(TYPE));
}
copyright
© sbVB
}
Arquivo binário (g++)
exemplo: copiando um arquivo binário
// unix, g++
#define TYPE unsigned char
void main()
{
TYPE buffer;
// to write, binary mode
ofstream writeFile;
ifstream readFile;
const char* fname = "c:\\xxx\\test.jpg";
const char* fname2 = "c:\\xxx\\test2.jpg";
readFile.open(fname);
if (!readFile)
writeFile.open(fname2);
if (!writeFile)
cout << "File " << fname2 << " not open";
while (true)
{
readFile.read((unsigned char*)&buffer, sizeof(TYPE));
if (readFile.eof()) break;
writeFile.write((unsigned char*)&buffer, sizeof(TYPE));
}
copyright
© sbVB
}
8
Tratamento de exceção
exception handling
n
Palavras reservadas para tratamento de
exceção
– try (tentar)
– catch (capturar)
– throw (jogar)
n
n
Em java o tratamento de exceção é muito
parecido com C++.
Tratamento de exceção é de certa forma
parecido com “goto”, mas respeita a
necessidade de se destruir os objetos.
copyright ©
sbVB
Bloco try-catch
linha de execução do programa
try
catch
catch
catch
bloco
try-catch
linha de execução do programa
copyright ©
sbVB
9
Exemplo de tratamento
de exceção
class SomeClass
{
public:
SomeClass() { cout << "SomeClass constructor" << endl; };
~SomeClass() { cout << "SomeClass destructor" << endl; };
};
float divide(float a, float b) // function under test
{
SomeClass testObject;
float ret;
if (b == 0)
throw "Can't divide by zero";
In main.
else
SomeClass constructor
ret = a / b;
SomeClass destructor
SomeClass testObject2;
EXCEPTION: Can't divide by zero
return ret;
Back in main.
}
void main()
{
cout << "In main." << endl;
try
{
float z = divide(1.1,0);
}
catch (const char *message)
{
cout << "EXCEPTION: " << message << endl;
}
cout << "Back
in ©main."
<< endl; http://www.del.ufrj.br/~villas
sbVB
copyright
}
bloco
try-catch
Mais de um catch handler
try
catch (catchHandler1)
copyright ©
sbVB
bloco
try-catch
10
class CatchHandler1
{
public:
const char *ShowExplanation() const
{ return "CatchHandler 1 Explanation"; }
};
class CatchHandler2
{
public:
};
void FunctionUnderTest(int i)
{
In main.
CatchHandler1 C1;
EXCEPTION CatchHandler
CatchHandler2 C2;
if (i == 1) throw C1;
Back in main.
if (i == 2) throw C2;
}
void main()
{
try
{
FunctionUnderTest(1);
}
catch (CatchHandler1 E)
{
cout << "EXCEPTION " << E.ShowExplanation() << endl;
}
{
}
cout << "Back in main." << endl;
}
Exemplo de mais de
um catch handler
1 Explanation
bloco
try-catch
Capturador genérico
generic catch
try {
catch
catch
catch
catch
copyright ©
throw obj4; }
(catchHandler1)
(catchHandler2)
(catchHandler3)
(...) // catch anything
sbVB
11
class CatchHandler1
{
public:
};
class CatchHandler2
{
public:
};
void main()
In main.
{
UNKNOWN EXCEPTION
try
Back in main.
{
throw 3.3; // throw double
}
{
}
{
}
catch (...) // generic catch
{
cout << "UNKNOWN EXCEPTION" << endl;
}
cout << "Back in main." << endl;
}
Exemplo de
capturador genérico
Exemplo de tratamento de exceção
no acesso a disco flexível
void openFile(ofstream & myFile)
{
const char *fileName = "a:\\t.txt";
ifstream auxFile;
auxFile.open(fileName, ios::nocreate); // check if file exists
if (auxFile) throw "file exists"; // if file exists
myFile.open(fileName); // try to open file to write
if (!myFile) throw "can't open file (is there a disk in drive?)";
}
copyright ©
sbVB
12
Exemplo (continuação)
void main()
{
ofstream myFile;
bool fileIsOpen = true;
try
{
openFile(myFile);
}
catch (const char *message)
{
cout << "EXCEPTION:" << message << endl;
fileIsOpen = false;
}
if (fileIsOpen)
{
cout << "Writing to file" << endl;
myFile << "test" << endl;
}
}
Casos:
1) OK (no exception)
2) EXCEPTION: file exists
copyright
© sbVB can't open
3) EXCEPTION:
file (is there a disk in drive?)
Namespace
Recurso de linguagem C++ para
isolamento de nomes.
n Não é estruturalmente um recurso de
“programação orientada a objetos”.
n
copyright ©
sbVB
13
Namespace (2)
This is the error handler of oneNamespace
This is the error handler of otherNamespace
namespace oneNamespace
{
void errorHandler()
{
cout << "This is the error handler of oneNamespace" << endl;
}
}
namespace otherNamespace
{
void errorHandler()
{
cout << "This is the error handler of otherNamespace" << endl;
}
}
void main()
{
oneNamespace::errorHandler();
otherNamespace::errorHandler();
copyright © sbVB
}
Namespace (3)
This is the error handler of oneNamespace
This is the error handler of otherNamespace
{
void errorHandler()
{
}
}
{
void errorHandler()
{
}
}
using namespace oneNamespace;
void main()
{
errorHandler(); // uses namespace oneNamespace by default
otherNamespace::errorHandler();
copyright © sbVB
}
14
Namespace (4)
{
void errorHandler()
{
}
}
{
void errorHandler()
{
}
}
using namespace oneNamespace;
using namespace otherNamespace;
void main()
{
errorHandler();
// error ! ambiguous
copyright © sbVB
}
Namespace aberto
(continuação do namespace)
{
void errorHandler()
{
}
}
{
void errorHandler()
{
}
}
namespace oneNamespace // continuation of oneNamespace
{
void otherFun()
{
cout << "otherFun of oneNamespace" << endl;
copyright © sbVB
}
}
15
Biblioteca padrão de C++
usando namespace std
Use headers sem extensão .h
n Todos os headers padrão foram reescritos com namespace.
n Não misture header padrão comum
(*.h) com header padrão usando
namespace (sem .h).
n
copyright ©
sbVB
Biblioteca padrão de C++
usando namespace (2)
#include <iostream>
#include <string>
void main ()
{
std::string s = "abc";
s += "def";
std::cout << s << endl;
}
#include <iostream>
#include <string>
using namespace std;
void main ()
{
string s = "abc";
s += "def";
cout << s << endl;
}
abcdef
copyright ©
sbVB
16
Não misture código com namespace
com código sem namespace
// certo, todos os headers na versão com namespce
#include<iostream>
#include<string>
// ...
// errado, misturando versões de header
// com namespace e sem namespace
#include<iostream>
#include<string.h>
// ...
copyright ©
sbVB
Adaptando uma biblioteca existente
para uso de namespace std
// mylib.h (versão sem namespace) header do usuário inclui
header padrão
class myClass {
public:
friend ostream & operator<<
(ostream & s, const myClass & obj);
};
// main.cpp (versão sem namespace)
outros headers
#include <string.h>
#include "mylib.h" // inclui iostream.h
void main ()
{
myClass a;
cout << a << endl;
}
copyright ©
sbVB
padrão
17
Adaptando uma biblioteca ... (2)
// mylib.h (versão adaptada)
#ifdef MYLIB_USE_NAMESPACE_STD
#include <iostream>
#else
#endif
class myClass {
public:
friend ostream & operator<<
(ostream & s, const myClass & obj);
};
// main.cpp, versão usando namespace std
// main.cpp, versão sem namespace std
#include <fstream>
#include <string>
#define MYLIB_USE_NAMESPACE_STD
#include <string.h>
#include "mylib.h"
#include "mylib.h"
void main () {
// daqui para baixo, o programa é igual
myClass a;
void main () {
cout << a << endl;
myClass a;
// ...
cout << a << endl;
}
// ...
copyright © sbVB
}
Exemplo de adaptação
// overload insersor
ostream & operator<<
(ostream & stream, const myClass & obj)
{
stream << obj.m_i << endl <<
obj.m_d << endl << obj.m_name;
class myClass
return stream;
{
}
int m_i;
// overload extrator
double m_d;
istream & operator>>
VBString m_name;
(istream & stream, myClass &obj)
public:
{
myClass()
stream >> obj.m_i;
{
stream >> obj.m_d;
m_i = 0;
stream >> obj.m_name;
m_d = 0;
return stream;
m_name = "UnNamed";
}
};
void main()
friend ostream & operator <<
{
(ostream & stream, const myClass &obj);
myClass a;
friend istream & operator>>
cout << a << endl;
(istream & stream, myClass &obj);
cout << "Entre i d nome : ";
};
cin >> a;
copyright © sbVB
cout << a << endl;
}
#include <fstream>
#define VBLIB_USE_NAMESPACE_STD
#include "vblib.h"
18
RTTI – Run Time Type Identification
Identificação de tipo em tempo de execução
n
Recurso incorporado recentemente ao C++.
– Compiladores “velhos” não dão suporte.
n
Novas palavras reservadas
–
–
–
–
–
typeid
dynamic_cast
static_cast
const_cast
reinterpret_cast
copyright ©
sbVB
RTTI – (2)
The type of i is int
The type of f is float
The type of a is class myClass
Same type
NOT SAME TYPE
#include <typeinfo.h>
class myClass { /* ... */ };
void printSameType(bool b)
{
if (b)
cout << "Same type" << endl;
else
cout << "NOT SAME TYPE" << endl;
}
void main()
{
int i, j;
float f;
myClass a;
cout << "The type of i is " << typeid(i).name() << endl;
cout << "The type of f is " << typeid(f).name() << endl;
cout << "The type of a is " << typeid(a).name() << endl;
bool sameType = (typeid(i) == typeid(j));
printSameType(sameType);
sameType = (typeid(i) == typeid(a));
copyright © sbVB
}
19
RTTI e late bind
The type of i is int
The type of f is float
The type of a is class myClass
Same type
NOT SAME TYPE
#include <typeinfo.h>
class myClass { /* ... */ };
void printSameType(bool b)
{
if (b)
cout << "Same type" << endl;
else
cout << "NOT SAME TYPE" << endl;
}
void main()
{
int i, j;
float f;
myClass a;
cout << "The type of i is " << typeid(i).name() << endl;
cout << "The type of f is " << typeid(f).name() << endl;
cout << "The type of a is " << typeid(a).name() << endl;
bool sameType = (typeid(i) == typeid(j));
sameType = (typeid(i) == typeid(a));
copyright © sbVB
}
20

Orientação a objetos

Transcrição

Documentos relacionados

Manipulação de Arquivos

Primeiro Programa em

4-Resumo C++

Aula 01 -2 - Mesonpi

TEP_Slides-02

3.1 inspection certificate according to en 10204 - 3.1

SY Sincero

Standard Library -

resumo- poster mercurialismo

Pesquisas relacionadas com teste Speedtest.net