Debug-specific code.md

Can you include code that only runs when compiling for debug? Yes !!!

You can use the cfg attribute with debug_assertions to run code only in debug builds:

fn my_function() {
    // This code always runs
    let x = 5;

    #[cfg(debug_assertions)]
    println!("Debug only: x = {}", x);  // Only runs in debug build

    // Or using if... just to be clear, this code is standalone and works as-is:
    if cfg!(debug_assertions) {
        println!("Also debug only!");
    }
}

When you build:

cargo build            # Debug build - code runs
cargo build --release  # Release build - code is removed

This is commonly used for debug logging, performance checks, or extra validation that you don't want in production code.