std::num::Int被deprecated了。所以只能用别人的crate或者自己实现Zero了。
github上有一个不错的： https://github.com/rust-num/num-traits 有关Zero的部分：
pub trait Zero: Sized + std::ops::Add<Self, Output = Self> { fn zero() -> Self; fn is_zero(&self) -> bool; } macro_rules! zero_impl { ($t:ty, $v:expr) => { impl Zero for $t { #[inline] fn zero() -> $t { $v } #[inline] fn is_zero(&self) -> bool { *self == $v } } }; } zero_impl!(usize, 0); zero_impl!(u8, 0); zero_impl!(u16, 0); zero_impl!(u32, 0); zero_impl!(u64, 0); #[cfg(has_i128)] zero_impl!(u128, 0); zero_impl!(isize, 0); zero_impl!(i8, 0); zero_impl!(i16, 0); zero_impl!(i32, 0); zero_impl!(i64, 0); #[cfg(has_i128)] zero_impl!(i128, 0); zero_impl!(f32, 0.0); zero_impl!(f64, 0.0);把这段复制一下就可以用Zerotrait了。 示例：
pub trait Zero: Sized + std::ops::Add<Self, Output = Self> { fn zero() -> Self; fn is_zero(&self) -> bool; } macro_rules! zero_impl { ($t:ty, $v:expr) => { impl Zero for $t { #[inline] fn zero() -> $t { $v } #[inline] fn is_zero(&self) -> bool { *self == $v } } }; } zero_impl!(usize, 0); zero_impl!(u8, 0); zero_impl!(u16, 0); zero_impl!(u32, 0); zero_impl!(u64, 0); #[cfg(has_i128)] zero_impl!(u128, 0); zero_impl!(isize, 0); zero_impl!(i8, 0); zero_impl!(i16, 0); zero_impl!(i32, 0); zero_impl!(i64, 0); #[cfg(has_i128)] zero_impl!(i128, 0); zero_impl!(f32, 0.0); zero_impl!(f64, 0.0); fn print<T: Zero + std::fmt::Display + std::clone::Clone>(x: T) { println!("{}", x); let test = vec![T::zero(); 10]; for x in test.iter() { println!("{}", x); } } fn main() { print(233); print(233.0); }输出：
233 0 0 0 0 0 0 0 0 0 0 233 0 0 0 0 0 0 0 0 0 0