Rust Result From Main. If you do failures will be printed along with any context and a backtrace if one was captured. Why Option and Result.
Example use std. Rust Programming Language Tutorials. Print the numbers on each line of a string multiplied by two.
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The main function in a Rust programme can return a Result type which allows you to provide feedback to users as well as setting the appropriate exit codes for the programme. The is_ok and is_err methods do what they say. Many languages use null nil undefined types to represent empty outputs and Exceptions to handle errors. Thread main panicked at NOT_AN_EVEN mainrs9 note.