Mem Functions

Memory-related functions

size_of และ align_of

use std::mem::{size_of, size_of_val, align_of, align_of_val};

fn main() {
    // size_of - type size
    println!("=== Type Sizes ===");
    println!("bool: {} bytes", size_of::<bool>());
    println!("char: {} bytes", size_of::<char>());
    println!("u8:   {} bytes", size_of::<u8>());
    println!("i32:  {} bytes", size_of::<i32>());
    println!("u64:  {} bytes", size_of::<u64>());
    println!("usize: {} bytes", size_of::<usize>());

    // Reference sizes
    println!("\n=== Reference Sizes ===");
    println!("&i32:    {} bytes", size_of::<&i32>());
    println!("&[i32]:  {} bytes", size_of::<&[i32]>());  // Fat pointer
    println!("&str:    {} bytes", size_of::<&str>());    // Fat pointer
    println!("Box<i32>: {} bytes", size_of::<Box<i32>>());

    // size_of_val - value size
    let arr = [1, 2, 3, 4, 5];
    println!("\n=== Value Sizes ===");
    println!("[i32; 5]: {} bytes", size_of_val(&arr));
    println!("slice: {} bytes", size_of_val(&arr[..]));

    // align_of
    println!("\n=== Alignment ===");
    println!("u8 align: {}", align_of::<u8>());
    println!("i32 align: {}", align_of::<i32>());
    println!("u64 align: {}", align_of::<u64>());

    // Struct padding
    struct Padded { a: u8, b: u32, c: u8 }
    println!("\nPadded struct: {} bytes (alignment: {})",
        size_of::<Padded>(), align_of::<Padded>());
}