Question

Suppose I have a struct called foo_boolean that contains some boolean values:

struct foo_boolean {
    bool b1;
    bool b2;
};

If I define a variable of type foo_boolean without initializing it, what will the default value of the member variables be? (i.e., true, false, or a random value of the two.)

Answer 1

It depends on how you create it. If the struct is constructed by default-initialization e.g.

void foo () {
  fool_boolen x;   // <---

then the values will be undefined (bad things will happen if you read it before setting a value).

On the other hand, if the struct is constructed by value-initialization or zero-initialization e.g.

fool_boolen x;   // <--

void foo2 () {
  static fool_boolen y; // <--
  fool_boolen z = fool_boolen();  // <--

then the values will be zero, i.e. false.