Question

I have a structure

   struct abc
   {
       struct xyz *ptr1; int *a;
   };

     struct xyz 
     {
         int *b;
        enum __boolean *filter;
     };

here
enum __boolean
{
false = 0;
true = 1;
};

I have declared a pointer to struct abc *ptr and have done a malloc,can any one pls tell me how to access the value in the enum, i want to assign the value.

I have done a malloc of all the structure

ptr->ptr1->filter = ? 

how to access the enum, i want to put the value zero there.

Answer 1

Since the struct field filter is a pointer to an enum, you need to dereference:

*ptr->ptr1->filter = false;

This is no different just because member is an enum, it would be exactly the same for any other directly assignable (“scalar”) type such as int or whatever.

You say you want to put the value “zero”, but since the type of filter is an enumeration, I guess you meant false.

Note also that in C99, we have stdbool.h> which gives bool and true and false. It’s best to use them, and not do an enum, if you can.