CObList::RemoveAll

void RemoveAll( );

说明：
从该列表中删除所有元素并释放与CObList关联的内存。若列表已经为空，也不产生错误。
当从CObList中删除元素时, 仅从列表中删除对象指针，对象本身得由自己删除。

示例：
CObList list;
CAge* pa1;
CAge* pa2;
ASSERT( list.IsEmpty()); // Yes it is.
list.AddHead( pa1 = new CAge( 21 ) );
list.AddHead( pa2 = new CAge( 40 ) ); // List now contains (40, 21).
ASSERT( !list.IsEmpty()); // No it isn't.
list.RemoveAll(); // CAge's aren't destroyed.
ASSERT( list.IsEmpty()); // Yes it is.
delete pa1; // Now delete the CAge objects.
delete pa2;