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Properties 6
get me and set me!
More On Indexed PropertiesDeclaring and Using Static Properties
More On Indexed Properties
An indexed property typically exposes a data structure that is accessed using a subscript operator. A default indexed property allows the user to access the data structure via the class name, whereas a user-defined indexed property requires the user to specify the property name to access the data structure. The following example shows how to use default and user defined indexed properties.
// property keyword, indexed property // compile with: /clr #include "stdafx.h"
using namespace System; |
public ref class myClass
{
array<int>^ MyArr;
public:
// constructor, 7 is the array size
myClass() { MyArr = gcnew array<int>(7); }
// default indexer
property int default[int]
{
int get(int index) { return MyArr[index]; }
void set(int index, int value) { MyArr[index] = value; }
}
// user-defined indexer
property int indexer1[int]
{
int get(int index) { return MyArr[index]; }
void set(int index, int value) { MyArr[index] = value; }
}
};
int main()
{
myClass ^ MyC = gcnew myClass();
// use the default indexer
Console::WriteLine("default indexer");
Console::Write("[ ");
for (int i = 0; i < 7; i++)
{
MyC[i] = i;
Console::Write("{0} ", MyC[i]);
}
Console::WriteLine("]");
// use the user-defined indexer
Console::WriteLine();
Console::WriteLine("user-defined indexer");
Console::Write("[ ");
for (int i = 0; i < 7; i++)
{
MyC->indexer1[i] = i * 2;
Console::Write("{0} ", MyC->indexer1[i]);
}
Console::WriteLine("]");
return 0;
}
Output:
The following example shows how to call the default indexer through the this pointer.
// call the default indexer through this pointer
// compile with: /clr
#include "stdafx.h"
using namespace System;
value class Position
{
public:
Position(int x, int y) : position(gcnew array<int, 2>(100, 100))
{ this->default[x, y] = 1; }
property int default[int, int]
{
int get(int x, int y) { return position[x, y]; }
void set(int x, int y, int value) {}
}
private:
array<int, 2> ^ position;
};
int main()
{
return 0;
}
// No output
The following example shows how you can use DefaultMemberAttribute to specify the default indexer.
// This is the main DLL file.
// specify the default indexer
// compile with: /LD /clr
#include "stdafx.h"
#include "specify_default_indexer.h"
using namespace System;
[Reflection::DefaultMember("XXX")]
public ref struct Squares
{
property Double XXX[Double]
{
Double get(Double data) { return data*data; }
}
};
The following example uses the metadata created in the previous example.
// use the default indexer
// compile with: /clr
#include "stdafx.h"
using namespace System;
#using "specify_default_indexer.dll"
int main()
{
Squares ^ square = gcnew Squares();
System::Console::WriteLine("{0}", square[3]);
return 0;
}
Output:
9
Declaring and Using Static Properties
The following program example shows how to declare and use a static property. A static property can only access static members of its class.
// more on property keyword
// compile with: /clr
#include "stdafx.h"
using namespace System;
ref class StaticProperties
{
static int MyInt;
static int MyInt2;
public:
static property int Static_Data_Member_Property;
static property int Static_Block_Property
{
int get() { return MyInt; }
void set(int value) { MyInt = value; }
}
};
int main()
{
StaticProperties::Static_Data_Member_Property = 100;
Console::WriteLine("StaticProperties::Static_Data_Member_Property: {0}",
StaticProperties::Static_Data_Member_Property);
StaticProperties::Static_Block_Property = 200;
Console::WriteLine("StaticProperties::Static_Block_Property: {0}", StaticProperties::Static_Block_Property);
return 0;
}
Output:
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