Macro_rules!
// This is a simple macro named `say_hello`.
macro_rules! say_hello {
// `()` indicates that the macro takes no argument.
() => {
// The macro will expand into the contents of this block.
println!("Hello!");
};
}
fn main() {
// This call will expand into `println!("Hello");`
say_hello!()
}
Ahmad Khaefi