Code

 Header...
typedef struct thing {
    double something;
    // More members here...
}Thing;

// Allocate a new Thing and read the values from stdin
 Thing* newThing(){
   ... 

»    Thing *p=NULL;
    
»    p=xmalloc(sizeof *p);
»    printf("Please enter the value of something\n");
»    scanf("%lg", &p->something);
    // etc.
 
»  return p;
}

 int main(){
   ... 

»    Thing *t=NULL;

»    t=newThing();

»    printf("%g\n", t->something);
»    return 0;
}