数组迭代

for 语句支持对数组进行迭代（但不支持元组）。

fn main() {
    let primes = [2, 3, 5, 7, 11, 13, 17, 19];
    for prime in primes {
        for i in 2..prime {
            assert_ne!(prime % i, 0);
        }
    }
}

此功能使用了 IntoIterator trait，但我们还没有讲到它。

The assert_ne! macro is new here. There are also assert_eq! and assert! macros. These are always checked, while debug-only variants like debug_assert! compile to nothing in release builds.