Journey to Rustacean

Rust

Rust Notes

Understanding Main function and Macros of Rust using Hello World.

// This is a comment
fn main() {
    println!("Hello, world!");
    // This prints hello, world with a \n by default
}

fn: funcation (like mini program)
main: the main functon, where the program begins
macro: (like built in function). How is it a macro? -> !
- print!: just a normal print. all output of multiple print! will be in one line without spaces
- println!: Prints each println! strings in different lines
Comments: //

Comments

// This is a comment
fn main() {
    println!("Hello, world!");
    /* 
    This is a 
    multi - line 
    comment
    block. (/* xyz */)
    */
}

Errors

fn main() {
    println!('Hello, world!');
}

In rust, when we want to declare a string, it needs to be in single quatation "xyz", not in single quatation.

Premitives: Integer

Scalar types: int, char, foat, boolean
unsigned: never -ve (u8, u16, u32, u64, u128, usize)
signed: can be -ve or +ve (i8, i16, i32, i64, i128, isize)
Default is i32 (best practice)

// {} -> Place holder
// MAX -> Max value that can be represented by this integer type
fn main() {
    println!("Max size of a u32: {}", u32::MAX);
}

Output: Max size of a u32: 4294967295

Premitives: Float

Floats: f32, f64
pi = 3.14

fn main() {
    println!("Max size of a f32: {}", f32::MAX);
    println!("Max size of a f64: {}", f64::MAX);
}
// Max size of a f32: 340282350000000000000000000000000000000
// Max size of a f64: 179769313486231570000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Premitives: boolean

True or False
representation: bool

Premitives: character

char - 4 bytes

Variables

let
variables in rust are immutable

fn main() {
    let hello = "Hello, world!";
    // let hello: &str = "Hello, world!";
    // let _hello = "Hello, world!";
    //      unused variable: `hello`, mute output
    println!("{}", hello);
}

Mutable variable

fn main() {
    let hello = "Hello, world!";
    println!("{}", hello);
    
}

More content soon!