Question

In the following code,
what’s the meaning of :next(next_par),info(info_par)?

struct list_node : public memory::SqlAlloc  
{ 
  list_node *next;  
  void *info;  
  list_node(void *info_par,list_node *next_par)  
    :next(next_par),info(info_par)   /* what's the meaning of :next(next_par),info(info_par)?*/
  {}  
  list_node()                    
  {  
    info= 0;  
    next= this;  
  }  
};  

looks like it wants to assign info_par to info for info(info_par), and assign next_par to next for next(next_par). But I didn’t see the definition of next(), info().

Answer 1

:next(next_par),info(info_par) is an initialization list for member variables. Instead of having:

list_node(void *info_par,list_node *next_par){
    next = next_par;
    info = info_par;
}

EDIT: Just as a note, initialization lists can be important if you have member object variables that need to be constructed with a non-default constructor.