How do I ignore an error returned from a Rust function and proceed regardless?

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Functions in Rust which can fail return a Result:

Result<T, E> is the type used for returning and propagating errors. It is an enum with the variants, Ok(T), representing success and containing a value, and Err(E), representing error and containing an error value.

I highly recommend reading the Error Handling section in the Rust Book:

Rust has a number of features for handling situations in which something goes wrong

If you want to ignore an error, you have different possibilities:

  • Don’t use the Result:

      let _ = failing_function();

    The function will be called, but the result will be ignored. If you omit let _ = , you will get a warning. As of Rust 1.59, you can omit the let and just write _ = failing_function();.

  • Ignore the Err variant of Result using if let or match:

      if let Ok(ret) = failing_function() {
      // use the returned value
  }

    You may also convert the Result into Option with Result::ok:

      let opt = failing_function().ok();

  • Unwrap the error. This code panics if an error occurred though:

      let ret = failing_function().unwrap();
  // or
  let ret = failing_function().expect("A panic message to be displayed");

try!() unwraps a result and early returns the function, if an error occurred. However, you should use ? instead of try! as this is deprecated.

See also:

  • What is this question mark operator about?
  • Is the question mark operator ? equivalent to the try! macro?
  • How to do error handling in Rust and what are the common pitfalls?

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