в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:29:22Z

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==Assign value to member variable directly from assignment==

<source lang="cpp">#include <iostream>
using namespace std;
class MyClass{
int a;
public:
MyClass(int j) {a = j;}
int geta(void) {return a;}
};
int main(void)
{
MyClass ob = 99;
cout << ob.geta();
}</source>

==Create a getter for member variable==

<source lang="cpp">#include <iostream>
using namespace std;
class MyClass{
int a;
public:
MyClass(int j) {a = j;}
int geta(void) {return a;}
};
int main(void)
{
MyClass ob = 99;
cout << ob.geta();
}</source>

==increment counter variable with ++ operator==

<source lang="cpp">#include <iostream>
using namespace std;
class Counter
{
private:
unsigned int count;
public:
Counter() : count(0){ }
unsigned int get_count(){ return count; }
void operator ++ (){
++count;
}
};
int main(){
Counter c1, c2;

cout << "\nc1=" << c1.get_count();
cout << "\nc2=" << c2.get_count();

++c1;
++c2;
++c2;

cout << "\nc1=" << c1.get_count();
cout << "\nc2=" << c2.get_count() << endl;
return 0;
}</source>

==Initialize member variable==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
class MyClass
{
public:
MyClass( int c = 0, int i = 1 );
void add()
{
count += increment;
}
void print() const;
private:
int count;
const int increment;
};
MyClass::MyClass( int c, int i ): count( c ),increment( i )
{
}
void MyClass::print() const
{
cout << "count = " << count << ", increment = " << increment << endl;
}
int main()
{
MyClass value( 10, 5 );
value.print();
for ( int j = 1; j <= 3; j++ )
{
value.add();
value.print();
}
return 0;
}</source>
<pre class=codeResult>count = 10, increment = 5
count = 15, increment = 5
count = 20, increment = 5
count = 25, increment = 5</pre>

==Initialize member variable in constructor==

<source lang="cpp">#include <iostream>
using namespace std;
class MyClass
{
public:
MyClass::MyClass(void);
void show_MyClass(void);
private:
int a;
int b;
int c;
};
MyClass::MyClass(void) : a(1), b(2), c(3) { };
void MyClass::show_MyClass(void)
{
cout << "a contains: " << a << endl;
cout << "b contains: " << b << endl;
cout << "c contains: " << c << endl;
}
int main(void)
{
MyClass numbers;
numbers.show_MyClass();
}</source>

==Output variable initialization message==

<source lang="cpp">#include <iostream>
using namespace std;
class MyClass
{
public:
int who;
MyClass(int id);
} global_obj1(1), global_obj2(2);
MyClass::MyClass(int id)
{
cout << "Initializing " << id << "\n";
who = id;
}
int main(void)
{
MyClass local_obj(3);
cout << "This is NOT the first line displayed.\n";
MyClass local_obj2(4);
}</source>

==Share static variable among different class instances==

<source lang="cpp">#include <iostream>
using namespace std;
class MyClass {
static int a;
int b;
public:
void set(int i, int j) {
a=i;
b=j;
}
void show();
};
int MyClass::a;
void MyClass::show(){
cout << "This is static a: " << a << endl;
cout << "This is non-static b: " << b << endl;
}
int main(void){
MyClass x, y;
x.set(1,1);
x.show();
y.set(2,2);
y.show();
x.show();
}</source>

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