Add struct to struct array using void pointer to said array in C -

let's have following struct , array of struct:

struct fileinfo {   int ascii[128];  //space store counts each ascii character.   int lnlen;       //the longest line’s length   int lnno;        //the longest line’s line number.   char* filename;  //the file corresponding struct. };  struct analysis fileinfo_space[8]; //space info 8 files 

i want have function add new struct array. must take void pointer position store struct argument

int addentry(void* storagespace){     *(struct fileinfo *)res = ??? //cast pointer struct pointer , put empty struct there     (struct fileinfo *)res->lnlen = 1; //change lnlen value of struct 1 } 

my questions are:

1. what goes in place of ??? tried (fileinfo){null,0,0,null} per this stackoverflow response. `error: ‘fileinfo’ undeclared (first use in function)

2. how create void pointer array? (void *)fileinfo_space correct?

i required use void * argument function assignment. it's not me.

let's have memory block passed storagespace void pointer:

you have define constant able initialize (unless you're using c++11), let's call init. btw assignment value wrong: first member array of int. cannot pass null it. zero-fill show below.

then cast void pointer pointer on struct, initialize copying init struct, modify @ will...

int addentry(void* storagespace){     static const struct fileinfo init = {{0},0,0,null};     struct fileinfo *fi = (struct fileinfo *)storagespace;     *fi = init; //cast pointer struct pointer , put empty struct there     fi->lnlen = 1; //change lnlen value of struct 1 }