Default Trait

Default value generation

Basic Usage

fn main() {
    // Built-in Default implementations
    let num: i32 = Default::default();  // 0
    let float: f64 = Default::default();  // 0.0
    let boolean: bool = Default::default();  // false
    let string: String = Default::default();  // ""
    let vec: Vec<i32> = Default::default();  // []
    let option: Option<i32> = Default::default();  // None

    println!("i32: {}", num);
    println!("f64: {}", float);
    println!("bool: {}", boolean);
    println!("String: {:?}", string);
    println!("Vec: {:?}", vec);
    println!("Option: {:?}", option);

    // Alternative syntax
    let s = String::default();
    let v = Vec::<i32>::default();

    println!("\nAlternative: {:?}, {:?}", s, v);

    // Collections
    use std::collections::HashMap;
    let map: HashMap<String, i32> = Default::default();
    println!("HashMap: {:?}", map);
}