Assign a single value to multiple variables in one line in Rust?

Question

A common way to assign multiple variables is often expressed in programming languages such as C or Python as:

a = b = c = value;

Is there an equivalent to this in Rust, or do you need to write it out?

a = value;
b = value;
c = value;

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Apologies if this is obvious, but all my searches lead to Q&A regarding tuple assignment.

Answer 1

You cannot chain the result of assignments together. However, you can assign multiple variables with a single statement.

In a let statement, you can bind multiple names by using an irrefutable pattern on the left side of the assignment:

let (a, b) = (1, 2);

(Since Rust 1.59, you can also have multiple values in the left side of any assignment, not just let statements.)

In order to assign the same value to multiple variables without repeating the value, you can use a slice pattern as the left-hand side of the assignment, and an array expression on the right side to repeat the value, if it implements Copy:

let value = 42;
let [a, b, c] = [value; 3]; // or: let [mut a, mut b, mut c] = ...
println!("{} {} {}", a, b, c); // prints: 42 42 42

(Playground)