Question 203525 in Visual Studio Code Question posted in
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Visual Studio Code – How to compare Enum value with u32

I have code something like this.

#[derive(PartialEq)]
enum FALUDA {
    Juice,
    Ice,
}

let a: u32 = 0;

if a == FALUDA::Juice {
 //Yay
}

If I try this code I am getting below error.

78 |     if a                 == FALUDA::Juice {
   |        --------             ^^^^^^^^^^^^^ expected `u32`, found `FALUDA`
   |        |
   |        expected because this is `u32`

I dont want to cast.

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2

Answers


  1. 0

    You need to cast the enum value to u32 (the type of a).

    Here is a complete example:

    #[derive(PartialEq)]
enum FALUDA {
    Juice,
    Ice,
}

fn main() {
    let a: u32 = 0;
    if a == FALUDA::Juice as u32 {
        print!("Juicy")
    }
}

    For simple cases casting really is all one should need. But if you need to do a lot of conversions from/to enum values, you might consider using a crate, such as strum_macros.

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  2. 0

    — Can we achieve something with match?

    Yes, you can implement PartialEq<FALUDA> for u32:

    #[derive(PartialEq)]
enum FALUDA {
    Juice,
    Ice,
}

impl PartialEq<FALUDA> for u32 {
    fn eq(&self, rhs: &FALUDA) -> bool {
        match rhs {
            FALUDA::Juice => self == &0,
            FALUDA::Ice => self == &1,
        }
    }
}

fn main() {
    let a: u32 = 0;

    if a == FALUDA::Juice {
        println!("Yay");
    }
}

    But this may prove unstable if you’d decide to change the order of FALUDA‘s variants.

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