Book Image

Rust Essentials - Second Edition

By : Ivo Balbaert
Book Image

Rust Essentials - Second Edition

By: Ivo Balbaert

Overview of this book

Rust is the new, open source, fast, and safe systems programming language for the 21st century, developed at Mozilla Research, and with a steadily growing community. It was created to solve the dilemma between high-level, slow code with minimal control over the system, and low-level, fast code with maximum system control. It is no longer necessary to learn C/C++ to develop resource intensive and low-level systems applications. This book will give you a head start to solve systems programming and application tasks with Rust. We start off with an argumentation of Rust's unique place in today's landscape of programming languages. You'll install Rust and learn how to work with its package manager Cargo. The various concepts are introduced step by step: variables, types, functions, and control structures to lay the groundwork. Then we explore more structured data such as strings, arrays, and enums, and you’ll see how pattern matching works. Throughout all this, we stress the unique ways of reasoning that the Rust compiler uses to produce safe code. Next we look at Rust's specific way of error handling, and the overall importance of traits in Rust code. The pillar of memory safety is treated in depth as we explore the various pointer kinds. Next, you’ll see how macros can simplify code generation, and how to compose bigger projects with modules and crates. Finally, you’ll discover how we can write safe concurrent code in Rust and interface with C programs, get a view of the Rust ecosystem, and explore the use of the standard library.
Table of Contents (13 chapters)

Binding variables to values


Storing all values in constants is not an option. It is not good because constants live as long as the program and moreover can't change, and often we want to change values. In Rust, we can bind a value to a variable by using a let binding.

// see Chapter 2/code/bindings.rs 
fn main() { 
  let energy = 5; // value 5 is bound to variable energy 
} 

Unlike in many other languages, such as Python or Go, the semicolon,;, is needed here to end the statement. Otherwise, the compiler throws an error, as follows:

error: expected one of `.`, `;`, or an operator, found `}`

We also want to create bindings only when they are used in the rest of the program, but don't worry, the Rust compiler warns us about that. The warning looks like the following:

    
values.rs:2:6: 2:7 warning: unused variable: `energy`, #[warn(unused_variables)] on by default
    
  

For prototyping purposes, you can suppress that warning by prefixing the variable name with an _, like in let _ energy = 5;...