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macro_rules! create_function {
// This macro takes an argument of designator `ident` and
// creates a function named `$func_name`.
// The `ident` designator is used for variable/function names.
($func_name:ident) => {
fn $func_name() {
// The `stringify!` macro converts an `ident` into a string.
println!("You called {:?}()",
stringify!($func_name));
}
};
}
// Create functions named `foo` and `bar` with the above macro.
create_function!(foo);
create_function!(bar);
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// 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!()
}