小编loc*_*kie的帖子

编译以下代码时:

use std::io::*;

fn main(){
    let reader = stdin();
    let nums = reader.lock()
        .lines().next().unwrap().unwrap()
        .split_whitespace()
        .map(|s| s.parse::<i32>().unwrap())
        .map(|s| s as f32)
        .map(|s| (s - 4) / 2)
        .map(|s| s as i32)
        .collect();
}

我收到一个错误说:

core::ops::Sub<_>该类型没有实现特征f32

为什么是这样？

我一直在尝试使用以下函数在m和n之间生成素数:

//the variable sieve is a list of primes between 1 and 32000
//The primes up to 100 are definitely correct
fn sieve_primes(sieve: &Vec<usize>, m: &usize, n: &usize) -> Vec<usize> {
    let size: usize = *n - *m + 1;
    let mut list: Vec<usize> = Vec::with_capacity(size);

    for i in *m..(*n + 1) {
        list.push(i);
    }   
    for i in sieve {
        for j in ( ((*m as f32) / (*i as f32)).ceil() as usize)..( (((*n as f32) / (*i as f32)).floor() …