How to initialize a union? [duplicate]

Answer 1

There is difference between initialization and assignment. Initialization is intelligent, while for the assignment you need to resolve proper address.

    Example
    char str[] = "xyz";    // works - initialization 
    char str[10];
    str = "xyz";            // error - assignment
                           // str is a address that can hold char not string

    Similarly
    Ptrlist l = {NULL};    // works - initialization 
    Ptrlist *l;
    l->next = NULL;        // works assignment
    l = {NULL};            // is assignment, don't know the address space error