[Solved! With two amazing answers!] How to increment in Rust?

help
2

The standard way to increment is with +=, so ss += 1;.

Rust doesn't provide a ++ operator for two primary reasons:

  • The primary motivator for ++ is for C-style for(init;condition;increment) loops, which aren't present at all in Rust. Instead, you use for pattern in iterator, so there's no need to manually increment your iterator cursor.
  • The ordering rules around ++ as an expression are nonobvious, even for experienced developers. On the other hand, += is a statement[1] with always clear ordering, and barely longer than ++ as a statement.

Language lawyer minutia and pedantry below.

[1]: Well, in actuality, += isn't a statement. place += value is an expression returning () ("unit", the type with only one value, the empty tuple). As far as I'm aware, there's only one actual statement in Rust: let[2]. Even assignment is just a ()-returning expression.

[2]: And there's experimental work that makes even that not true, allowing the use of let as an expression (in some restricted contexts).

2 Likes