Add `#![no_std]` to the top of your `main.rs` file to disable the standard library. This forces the compiler to use only the core library, which is essential for embedded systems or bare-metal programming.

How to Write Rust Code Without the Standard Library

Add #![no_std] to the top of your main.rs file to disable the standard library. This forces the compiler to use only the core library, which is essential for embedded systems or bare-metal programming.

#![no_std]
#![no_main]

use core::panic::PanicInfo;

#[panic_handler]
fn panic(_info: &PanicInfo) -> ! {
    loop {}
}

#[no_mangle]
pub extern "C" fn main() -> i32 {
    // Your code here
    0
}

Note: You must also add #![no_main] and define a custom entry point if you are targeting bare-metal environments without an OS.

Writing Rust code without the standard library tells the compiler to exclude common tools like file I/O and network access. You use this approach when building for devices with very limited memory, like microcontrollers, where those tools are too heavy. Think of it as packing only the absolute essentials for a trip instead of your whole house.