rust - Rust 中的文字字符串和 Args 有什么区别？

Question

我有一个使用正则表达式的字符串解析函数:fn parse(s: &str) -> Option<MyObj> .它在使用 parse("test string") 进行测试时有效.但是在使用 Args 时失败了.失败是正则表达式无法匹配 s 中的任何内容.

我使用的方式 Args是:args().map(|arg| parse(&arg)).collect() .我在这里看不到类型错误。和 println在parse显示s与“测试字符串”相同的字符串。

---

更新了我的描述。我不确定我的问题是否与 String 和 str 的不同有关。因为我用的是 str还是失败了。

extern crate regex;

use regex::Regex;
use std::env::args;

struct IPRange {
    start: u32,
    mask: u8,
}

fn parse_iprange(ipr: &str) -> Option<IPRange> {
    let parser = Regex::new(
        r"^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/(\d+|\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})$",
    )
    .unwrap();
    let caps = parser.captures(ipr).unwrap();
    return Some(IPRange { start: 0, mask: 0 });
}

fn main() {
    let v: Vec<_> = args().map(|arg| parse_iprange(&arg)).collect();
}

$ RUST_BACKTRACE=1 cargo run 192.168.3.1/24
    Finished dev [unoptimized + debuginfo] target(s) in 0.04s
     Running `target/debug/ip_helper 192.168.3.1/24`
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:345:21
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:70
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:58
             at src/libstd/panicking.rs:200
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:215
   4: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:478
   5: std::panicking::continue_panic_fmt
             at src/libstd/panicking.rs:385
   6: rust_begin_unwind
             at src/libstd/panicking.rs:312
   7: core::panicking::panic_fmt
             at src/libcore/panicking.rs:85
   8: core::panicking::panic
             at src/libcore/panicking.rs:49
   9: <core::option::Option<T>>::unwrap
             at /rustc/2aa4c46cfdd726e97360c2734835aa3515e8c858/src/libcore/macros.rs:10
  10: ip_helper::parse_iprange
             at src/main.rs:18

Answer 1

args()的第一项是实现行为:

The first element is traditionally the path of the executable, but it can be set to arbitrary text, and may not even exist. This means this property should not be relied upon for security purposes.

因此，您应该跳过它:

let v: Vec<_> = args().skip(1).map(|arg| parse_iprange(&arg)).collect();