Code Fix

中級E0502: cannot borrow as mutable because it is also borrowed as immutable › パターン5

E0502: cannot borrow as mutable because it is also borrowed as immutable

不変参照が生きている(後で使われる)間に、同じ変数を可変で借用しようとするとE0502エラーになります。

 1  fn main() {
 2      let mut scores = vec![70, 80];
 3      let top = &scores[1];
 4      _________________
                ^
 5      println!("{}", top);
 6  }
error[E0502]: cannot borrow `scores` as mutable because it is also borrowed as immutable

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E0502: cannot borrow as mutable because it is also borrowed as immutable

Rustの借用規則は「不変参照は何個でも、可変参照は同時に1つだけ」を強制します。

このエラーの解説と類題をまとめて見る →

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