Matching Vec<&str> is possible?

help
1

help
help906×554 146 KB

Why never matching? the vector have the info but the matching never occurs.

thanks

2

The vector will only match that pattern if the vector has length one. It seems like your vector has multiple elements.

9 Likes
3

Solution:

// Rough translation of the iteration without a `for` iterator.
let mut it = values.into_iter();
loop {
    match it.next() {
        Some(x) => println!("{}", x),
        None => break,
    }
}

https://brson.github.io/rust-anthology/1/effectively-using-iterators.html

4

Perhaps you meant the pattern [_, "APP_ENV=local"], but more likely you want <[T]>::contains():

if sort_data.contains(&"APP_ENV=local") {
    println!("Send RCE");
    // ...
}
4 Likes
5

Thanks bro but i don't want to use IF of every case i think match are more idiomatic!

6

If you want to check the second value in the array against a series of values, then indeed, match is more idiomatic. Like:

match sort_data[1] {
    "..." => { /* ... */ }
    // ...
}

However, if you want to test for some values if contained in the array, separately, then match is not meant for that, even if the syntax is nice. A series of ifs is the right thing to do. (there are some other clever possibilities with iterators, however).

3 Likes
7

If you may or may not have multiple elements, why not use the .. operator with your match?

match sort_data[..] {
  ["APP_ENV=local", ..] => todo!(),
  _ => todo!(),

}

You can also bind the rest of the slice to a variable with @ (e.g. ["APP_ENV=local", rest @ ..]).

5 Likes
8

it doesn't work bro the code for work is

let mut it = values.into_iter();
loop {
    match it.next() {
        Some(x) => println!("{}", x),
        None => break,
    }
}

if the match don't have a value defined into the match never enter in the Vector, in others words: Match can't work whit ranges.

9

Can you say more than "it doesn't work". If you show us the compile error then we can help you debug it.

It works just fine for me:

fn main() {
    let a = vec!["first", "second", "third"];
    let b = vec!["fourth", "fifth", "sixth"];
    let c = vec!["seventh"];

    print(a);
    print(b);
    print(c);
}

fn print(item: Vec<&str>) {
    match item[..] {
        ["first", ..] => println!("Starts with first"),
        ["fourth", ..] => println!("Starts with fourth"),
        _ => println!("Starts with something else"),
    }
}

(playground)

10

I just checked your screenshot in more detail... Your problem is that sort_data is a vec!["APP_NAME=SmartJack", "APP_ENV=local"]. The APP_ENV=local is the second element, yet all the proposed solutions have expected APP_ENV=local to be the first.

Your loop works because it'll fail the check on the first pass then find APP_ENV=local on the second time through.

To match on the second item you could do something like this:

match sort_data[..] {
    [_, "APP_ENV=local", ..] => println!("Found the local env"),
    _ => println!("Ssomething else"),
}
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