Optionale Typen deklarieren

Real programs hit cases where a value is simply absent: a lookup misses, a field is empty. Zig models this absence safely and on purpose.

An optional type can hold either a real value of some type, or the special value null meaning nothing is there.

You make any type optional by writing ? in front of it. So ?i32 is an integer that might also be null.

An optional happily holds a normal value too. You assign 42 to an ?i32 exactly as you would assign to a plain i32.

The keyword null is the literal that means there is no value. Only optional types are allowed to hold it.

A plain i32 can never be null. The compiler stops you, so absence stays visible in the type rather than hiding as a bad value.

Optionals are not just for numbers. You can mark a bool, a struct, a slice, or any type as optional by adding the question mark.

Assign an optional value and Zig infers the optional type for you, so you do not always have to spell it out by hand.

In C people fake absence with values like -1 or a null pointer. Zig gives you a real optional so absence cannot be confused with data.

Because ? lives in the type itself, anyone reading your code instantly sees that a value might be missing and must be handled.

It is common to start an optional at null and fill it in later once you actually have the value to store.

How do you declare a u32 that might be missing?

You met optionals: write ? before a type to allow a real value or null. Absence now lives in the type, plain and visible. ❓