Posted on 2011-03-08 10:35
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02 編程語言
指針可以指向基本類型，也可以指向復合類型，因此也可以指向另外一個指針變量，稱為指向指針的指針。
int i;
int *pi = &i;
int **ppi = π這樣定義之后，表達式*ppi取pi的值，表達式**ppi取i的值。請讀者自己畫圖理解i、pi、ppi這三個變量之間的關系。
案例：遞歸查找對象并返回對象指針
bool CustomEntity::getEntityByPart(const String& partID, graphics::IEntity* inEntity, graphics::IEntity** outEntity)
{
//
if (inEntity && (inEntity->getPartID() == partID))
{
return true;
}
//
graphics::EntityPtrList::iterator iter;
if(inEntity->getSkeleton())
{
graphics::EntityPtrList entityList = inEntity->getSkeleton()->getEntities();
for (iter = entityList.begin(); iter != entityList.end(); ++ iter)
{
graphics::IEntity* entity = *iter;
if(getEntityByPart(partID, entity, outEntity))
{
*outEntity = entity;
return true;
}
}
}
return false;
}
bool CustomEntity::getEntityByPart(const String& partID, graphics::IEntity** outEntity)
{
int num = model_->numComponents();
for (int i = 0; i < num; ++i)
{
model::ModelComponent *mc = model_->getComponentByIndex(i);
if (mc->getType() == model::ModelComponent::MCT_GRAPHIC)
{
model::Graphical *gc = static_cast<model::Graphical *>(mc);
model::Graphical::TagEntityMap::iterator itEntity = gc->entities_.begin();
model::Graphical::TagEntityMap::iterator itEnd = gc->entities_.end();
while (itEntity != itEnd)
{
graphics::IEntity* entity = itEntity->second.p_;
if(getEntityByPart(partID, entity, outEntity))
{
*outEntity = entity;
return true;
}
++itEntity;
}
}
}
return false;
}