words per minute
1
2209010116
00:00
Speed
fn add(a: i32, b: i32) -> i32 {
a + b // 注意：没有分号！最后一个表达式就是返回值
}
fn describe(label: &str, value: i32) {
println!("{}: {}", label, value);
}
fn main() {
let x: i32 = 42; // 显式类型标注，不可变
let mut count = 0; // 类型推导，可变
count += 1;
count += 1;
println!("x = {}, count = {}", x, count);
let sum = add(x, count);
describe("sum", sum);
// x = 100; // ← 取消注释试试，编译器会报错！
let is_big = x > 100;
println!("x > 100 ? {}", is_big);
}