Data Macros

Macros สำหรับ data structures และ collections

vec! Macro

fn main() {
    // Create Vec with values
    let v1 = vec![1, 2, 3, 4, 5];
    println!("v1: {:?}", v1);

    // Repeat value
    let v2 = vec![0; 5];  // [0, 0, 0, 0, 0]
    println!("v2: {:?}", v2);

    // Complex types
    let strings = vec!["hello".to_string(), "world".to_string()];
    println!("strings: {:?}", strings);

    // Nested
    let matrix = vec![
        vec![1, 2, 3],
        vec![4, 5, 6],
        vec![7, 8, 9],
    ];
    println!("matrix: {:?}", matrix);

    // With expressions
    let computed = vec![1 + 1, 2 * 2, 3 * 3];
    println!("computed: {:?}", computed);

    // Empty Vec with type
    let empty: Vec<i32> = vec![];
    println!("empty: {:?}", empty);

    // Capacity hint (not size)
    let mut with_cap = Vec::with_capacity(100);
    with_cap.extend(vec![1, 2, 3]);
    println!("with_cap len: {}, cap: {}", with_cap.len(), with_cap.capacity());
}