C-Void pointer inside a generic list (Contains stucture) -

i have 2 different stuctures need contain them in same generic list.

the structures :

     typedef struct val1{        int num1;        int num2;        int num3;      }val1;        typedef struct val2{      char name[50];      char surname[50];      int id;     }val2; 

and list is:

typedef stuct list {   void *value;   struct node *next; }list;  typedef struct l_head{  node *head;  int num_members;  }l_head; 

i need use same list implementation list needs handle both of strucrure types.i cant figure out how initialize list , put elements in list .any advice helpfull.

the canonical solution c add common initial field having distinct values both structures.

typedef struct val1 {     int discriminator;     int num1;     int num2;     int num3;  } val1;  typedef struct val2 {     int discriminator;     char name[50];     char surname[50];     int id; } val2; 

if neccessary, can define new struct instead.
has advantage of preserving previous layout , alignment guarantees:

struct packed {     int discriminator;     union {struct val1;struct val2}; }; 

anyway, integrate directly node:

typedef stuct node {     struct node *next;     int discriminator; /* might want reserve 0 no content */     union {struct val1;struct val2}; } node; 

the technical term of solution "discriminated union".