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rustintegerdata-conversionoctal

In rust, convert a string representation of an octal into a u32

I'm using the following code to convert a string representation of an octal into a u32:

pub fn umask() -> String {
    match env::var("UMASK") {
        Ok(res) => res.into(),
        _ => "777".into()
    }
}

fn main() {
    println!("{:#?}", u32::from_str_radix(format!("0o{}", umask()).as_str(), 8));
}

Instead all I Get is:

Err(
    ParseIntError {
        kind: InvalidDigit,
    },
)

According to this it looks like it's in the correct format and as it's an octal, it's base 8 thus a radix of 8 is what you need.

What am I doing wrong?

Solution

  • Drop the 0o prefix. from_str_radix does not expect any kind of a prefix, as the radix is already given as a separate argument.

    fn main() -> Result<(), Box<dyn std::error::Error>> {
    println!("{}", u32::from_str_radix("777", 8)?); // Prints: 511
    println!("{}", u32::from_str_radix("0777", 8)?); // Prints: 511
    Ok(())
}