Ziglings 38 undefined variable

[glad talon]

I am working my way through Ziglings and I am currently on exercise 38. Here is part of the exercise:

var chars: [2]Character = undefined;
// Glorp the Wise
chars[0] = Character{
    .role = Role.wizard
    .gold = 20,
    .health = 100,
    .experience = 10,
};

// Please add "Zump the Loud" with the following properties:
//
//     role       bard
//     gold       10
//     health     100
//     experience 20
//
//Feel free to run this program without adding Zump. What does
//it do and why?
// Printing all RPG characters in a loop:                                                                          
for (chars, 0..) |c, num| {
    std.debug.print("Character {} - G:{} H:{} XP:{}\n", .{
        num + 1, c.gold, c.health, c.experience,
    });
}

In this case, I never set the value at index 1 in the array.
When I compile and run it prints Character 2 - G:2863311530 H:170 XP:2863311530 which is 0xAAAAAAAA and is the default value for undefined memory.

My question is, why does this compile and run without warnings/errors/runtime crash?
to read an undefined value should not be allowed, or?

[rocky harbor]

Because 0xAA... is a debug value, is not undefined behaviour to print undefined value, is an undefined behaviour to control flow over undefined values

if you did an IF or something on undefined, that's undefined, behaviour, if you had it in a ptr, etc.

0xAAAA is just a pattern easy to spot

As you can see, you noticed that it was 0xaaaa quite easily

Now you know that value is undefined