Object Create Operator new
The new operator automatically creates an object of a corresponding size, calls the object constructor and returns a descriptor of created object. In case of failure, the operator returns a null descriptor that can be compared with the NULL constant.
The new operator can be applied only to class objects. It can't be applied to structures.
The operator shall not be used to create arrays of objects. To do this, use the ArrayResize() function.
Example:
//+------------------------------------------------------------------+
//| Figure creation |
//+------------------------------------------------------------------+
void CTetrisField::NewShape()
{
m_ypos=HORZ_BORDER;
//--- randomly create one of the 7 possible shapes
int nshape=rand()%7;
switch(nshape)
{
case 0: m_shape=new CTetrisShape1; break;
case 1: m_shape=new CTetrisShape2; break;
case 2: m_shape=new CTetrisShape3; break;
case 3: m_shape=new CTetrisShape4; break;
case 4: m_shape=new CTetrisShape5; break;
case 5: m_shape=new CTetrisShape6; break;
case 6: m_shape=new CTetrisShape7; break;
}
//--- draw
if(m_shape!=NULL)
{
//--- pre-settings
m_shape.SetRightBorder(WIDTH_IN_PIXELS+VERT_BORDER);
m_shape.SetYPos(m_ypos);
m_shape.SetXPos(VERT_BORDER+SHAPE_SIZE*8);
//--- draw
m_shape.Draw();
}
//---
} |
It should be noted that object descriptor is not a pointer to memory address.
An object created with the new operator must be explicitly removed using the delete operator.
See also
Initialization of Variables, Visibility Scope and Lifetime of Variables, Creating and Deleting Objects
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