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stringinttype-conversionrust

How do I convert from an integer to a string?


I am unable to compile code that converts a type from an integer to a string. I'm running an example from the Rust for Rubyists tutorial which has various type conversions such as:

"Fizz".to_str() and num.to_str() (where num is an integer).

I think the majority (if not all) of these to_str() function calls have been deprecated. What is the current way to convert an integer to a string?

The errors I'm getting are:

error: type `&'static str` does not implement any method in scope named `to_str`
error: type `int` does not implement any method in scope named `to_str`

Solution

  • Use to_string() (running example here):

    let x: u32 = 10;
    let s: String = x.to_string();
    println!("{}", s);
    

    You're right; to_str() was renamed to to_string() before Rust 1.0 was released for consistency because an allocated string is now called String.

    If you need to pass a string slice somewhere, you need to obtain a &str reference from String. This can be done using & and a deref coercion:

    let ss: &str = &s;   // specifying type is necessary for deref coercion to fire
    let ss = &s[..];     // alternatively, use slicing syntax
    

    The tutorial you linked to seems to be obsolete. If you're interested in strings in Rust, you can look through the strings chapter of The Rust Programming Language.