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

#[repr(C)]
#[derive(Debug)]
struct MyStruct {
    id: u32,
    flag: bool,
}

fn main() {
    let data = MyStruct { id: 42, flag: true };

    // Print field values
    println!("MyStruct: {:?}", data);

    // Print size and alignment info
    println!("Size of MyStruct: {} bytes", size_of::<MyStruct>());
    println!("Alignment of MyStruct: {} bytes", align_of::<MyStruct>());

    // Get raw bytes (unsafe for demonstration only)
    let ptr = &data as *const MyStruct as *const u8;
    let raw_bytes = unsafe { std::slice::from_raw_parts(ptr, size_of::<MyStruct>()) };

    println!("Raw bytes: {:?}", raw_bytes);
}
by

Rust online compiler

Write, Run & Share Rust code online using OneCompiler’s Rust online compiler for free. It’s a fast, interactive, and powerful environment to learn and experiment with the Rust programming language. OneCompiler runs the latest stable version of Rust.

About Rust

Rust is a systems programming language developed by Mozilla that focuses on performance, memory safety, and concurrency. It guarantees memory safety without a garbage collector and is widely used for system-level programming, web assembly, and command-line tools. Rust's compiler enforces strict compile-time checks, making code safer and more predictable.

Sample Code

The following is a simple Rust program that prints a greeting:

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

Taking inputs (stdin)

OneCompiler’s Rust editor supports stdin. Here’s a sample program that reads a line of input and prints it:

use std::io;

fn main() {
    let mut input = String::new();
    io::stdin()
        .read_line(&mut input)
        .expect("Failed to read line");
    println!("Hello, {}", input.trim());
}

Syntax Basics

Variables

let name = "OneCompiler";        // Immutable
let mut age = 25;                // Mutable

Data Types

TypeDescription
i32, i64Signed integers
f32, f64Floating-point numbers
booltrue or false
charSingle character
StringGrowable string

Conditionals

let score = 85;
if score >= 50 {
    println!("Pass");
} else {
    println!("Fail");
}

Loops

For loop

for i in 1..=5 {
    println!("{}", i);
}

While loop

let mut i = 1;
while i <= 5 {
    println!("{}", i);
    i += 1;
}

Loop (infinite with break)

let mut count = 0;
loop {
    if count == 3 {
        break;
    }
    println!("{}", count);
    count += 1;
}

Functions

fn add(a: i32, b: i32) -> i32 {
    a + b
}

fn greet(name: &str) {
    println!("Hello, {}!", name);
}

This guide provides a quick reference to Rust programming syntax and features. Start coding in Rust using OneCompiler’s Rust online compiler today!