Rust Brain Teasers/

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Puzzle 9: Explanation

Puzzle 9: Explanation

Let’s find out how sorting floating-point numbers work in Rust.

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Test it out

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fn main() {
    let mut floats = vec![3.1, 1.2, 4.5, 0.3];
    floats.sort();
    println!("{:#?}", floats);
}

Explanation

Rust makes it easy to sort vectors of most types. The sort() function can sort a vector of strings alphabetically or a vector of integers numerically without issue. So, why doesn’t sorting a vector of floating-point numbers work?

Since floating-point numbers aren’t always numbers, they aren’t always naturally sortable. Rust generally makes sorting values easy, but it’s also careful to avoid implicit behavior that can surprise the programmer. Consider the following “impossible” math calculations:

  • The tangent of 90° is infinity, so there’s no appropriate result.
  • Division by
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