в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:29:25Z

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==Cascading member function calls with the this pointer==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
#include <iomanip>
using std::setfill;
using std::setw;
class Time
{
public:
Time( int = 0, int = 0, int = 0 );
Time &setTime( int, int, int );
Time &setHour( int );
Time &setMinute( int );
Time &setSecond( int );
int getHour() const;
int getMinute() const;
int getSecond() const;
void printUniversal() const;
private:
int hour;
int minute;
int second;
};
Time::Time( int hr, int min, int sec )
{
setTime( hr, min, sec );
}
Time &Time::setTime( int h, int m, int s )
{
setHour( h );
setMinute( m );
setSecond( s );
return *this;
}
Time &Time::setHour( int h )
{
hour = h;
return *this;
}
Time &Time::setMinute( int m )
{
minute = m;
return *this;
}
Time &Time::setSecond( int s )
{
second = s;
return *this;
}
int Time::getHour() const
{
return hour;
}
int Time::getMinute() const
{
return minute;
}
int Time::getSecond() const
{
return second;
}
void Time::printUniversal() const
{
cout << hour << ":" << minute << ":" << second;
}
int main()
{
Time t;
t.setHour( 18 ).setMinute( 30 ).setSecond( 22 );
t.printUniversal();
t.setTime( 20, 20, 20 ).printUniversal();
cout << endl;
return 0;
}</source>
<pre class=codeResult>18:30:2220:20:20</pre>

==Returning the dereferenced this pointer==

<source lang="cpp">#include <iostream>

class MyType
{
public:
MyType();
~MyType(){}
int getValue()const {
return myValue;
}
void setValue(int x) {
myValue = x;
}
const MyType& operator++ (); // prefix
const MyType operator++ (int); // postfix

private:
int myValue;
};

MyType::MyType(): myValue(0) {}

const MyType& MyType::operator++()
{
++myValue;
return *this;
}

const MyType MyType::operator++(int)
{
MyType temp(*this);
++myValue;
return temp;
}

int main()
{
MyType i;
std::cout << "The value of i is " << i.getValue() << std::endl;
i++;
std::cout << "The value of i is " << i.getValue() << std::endl;
++i;
std::cout << "The value of i is " << i.getValue() << std::endl;
MyType a = ++i;
std::cout << "The value of a: " << a.getValue();
std::cout << " and i: " << i.getValue() << std::endl;
a = i++;
std::cout << "The value of a: " << a.getValue();
std::cout << " and i: " << i.getValue() << std::endl;
return 0;
}</source>
<pre class=codeResult>The value of i is 0
The value of i is 1
The value of i is 2
The value of a: 3 and i: 3
The value of a: 3 and i: 4</pre>

==Use the "this" pointer.==

<source lang="cpp">#include <iostream>
using namespace std;

class MyClass {
int i;
public:
void setI(int val) {
this->i = val;
}
int getI() {
return this->i;
}
} ;

int main()
{
MyClass o;

o.setI(100);
cout << o.getI();

return 0;
}</source>
<pre class=codeResult>100</pre>

==Using the this pointer==

<source lang="cpp">#include <iostream>

class Rectangle
{
public:
Rectangle();
~Rectangle();
void SetLength(int length) { this->itsLength = length; }
int GetLength() const { return this->itsLength; }
void SetWidth(int width) { itsWidth = width; }
int GetWidth() const { return itsWidth; }

private:
int itsLength;
int itsWidth;
};

Rectangle::Rectangle()
{
itsWidth = 5;
itsLength = 10;
}

Rectangle::~Rectangle()
{}

int main()
{
Rectangle theRect;
std::cout << "theRect is " << theRect.GetLength()
<< " feet long.\n";
std::cout << "theRect is " << theRect.GetWidth()
<< " feet wide.\n";

theRect.SetLength(20);
theRect.SetWidth(10);
std::cout << "theRect is " << theRect.GetLength()
<< " feet long.\n";
std::cout << "theRect is " << theRect.GetWidth()
<< " feet wide.\n";

return 0;
}</source>
<pre class=codeResult>theRect is 10 feet long.
theRect is 5 feet wide.
theRect is 20 feet long.
theRect is 10 feet wide.</pre>

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