Class interactions

Working with multiple classes that interact can cause some problems. Here are some tips:

• To use each of two classes within the other, you need to declare the second one before using it in the first:
  class secondclass; 
  class firstclass{ 
     secondclass* foo; 
  ...} 
  class secondclass{ 
     firstclass* foo2; 
  ...}
• To pass a pointer to a object into another object, memory for the object must already be allocated:
  • //this doesn't work:
    parm2* Z;  
    parm* a=new parm(Z); 
    Z=new parm2();
  • //Instead, you need to pass the allocated location of Z to a
    parm* a=new parm(); 
    parm2* Z=new parm2(); 
    a->associate(Z); /* associate is a member function of parm that makes use of Z; e.g. it could create a member object of 'a' that points to *Z */