I'm wondering what's the difference between sample1 and sample2. Why sometimes I have to pass the struct as an argument and sometimes I can do it without passing it in the function? and how would it be if samplex function needs several structs to work with? would you pass several structs as an argument?

struct x
{
    int  a;
    int  b;
    char *c;
};

void sample1(struct x **z;){
    printf(" first member is %d \n", z[0]->a);
}

void sample2(){
    struct x **z;
    printf(" first member is %d \n", z[0]->a); // seg fault
}

int main(void)
{
    struct x **z;

    sample1(z);
    sample2();

    return 0;
}