Getting Started

Hello_World.rs

fn main() {
    println!("Hello, World!");
}

Compiling and Running

$ rustc Hello_World.rs
$ ./Hello_World
Hello, World!

Primitive types

bool	Boolean (true / false)
char	character
f32, f64	32-bits, 64-bits floats
i64, i32, i16, i8	signed 16- ... integers
u64, u32, u16, u8	unsigned 16-bits, ... integers
isize	pointer-sized signed integers
usize	pointer-sized unsigned integers

Formatting

// Single Placeholder
println!("{}", 1);

// Multiple Placeholder
println!("{} {}", 1, 3);

// Positional Arguments
println!(
    "{0} is {1} {2}, also {0} is a {3} programming language",
    "Rust", "cool", "language", "safe"
);

// Named Arguments
println!(
    "{country} is a diverse nation with unity.",
    country = "India"
);

// Placeholder traits :b for binary, :0x is for hex and :o is octal
println!("Let us print 76 is binary which is {:b} , and hex equivalent is {:0x} and octal equivalent is {:o}", 76, 76, 76);

// Debug Trait
println!(
    "Print whatever we want to here using debug trait {:?}",
    (76, 'A', 90)
);

// New Format Strings in 1.58
let x = "world";
println!("Hello {x}!");

Printing Styles

// Prints the output
print!("Hello World\n");

// Appends a new line after printing
println!("Appending a new line");

// Prints as an error
eprint!("This is an error\n");

// Prints as an error with new line
eprintln!("This is an error with new line");

Variables

// Initializing and declaring a variable
let some_variable = "This_is_a_variable";

// Making a variable mutable
let mut mutable_variable = "Mutable";

// Assigning multiple variables
let (name, age) = ("ElementalX", 20);

// (Global) constant
const SCREAMING_SNAKE_CASE: i64 = 9;

Comments

// Line Comments
/*.............Block Comments */
/// Outer doc comments
//! Inner doc comments

See: Comment

Functions

fn test() {
    println!("This is a function!");
}

fn main() {
    test();
}

Comments