they_are_functions_in_bevy.md

They Are Functions In Bevy

To execute a function in Bevy, we need to add a System to the App through the add_systems method. One type of the System is a function without parameters. We pass the name of the function (hello in the following code) to the add_systems method.

use bevy::app::{App, Startup};

fn main() {
    App::new().add_systems(Startup, hello).run();
}

fn hello() {
    println!("Hello world!");
}

Output:

Hello world!

In addition to the name of the function, we also specify when to execute the function. In the code above, we specify Startup as the moment to execute the hello function.

➡️ Next: The Default Scheduler For Systems

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