theorem square_diff_nat (a b: ℕ) (h: b ≤ a) : a ^ 2 - b ^ 2 = (a + b) * (a - b) := bycalca ^ 2 - b ^ 2= a * a - b * b := by repeat rw [Nat.pow_two]_ = a * a - b * b + 0 := by rw [add_zero (a * a - b * b)]_ = a * a - b * b + (a * b - a * b) := by rw [←Nat.sub_self (a * b)]have h1: a * b ≤ a * b := by rflhave h2: b * b ≤ a * a := Nat.mul_self_le_mul_self hcalc_ = a * a + (a * b - a * b) - b * b := by rw[←Nat.sub_add_comm h2]_ = a * a + a * b - a * b - b * b := by rw [← Nat.add_sub_assoc h1]_ = a * (a + b) - (b * (a + b)) := by rw[←Nat.mul_add, Nat.sub_sub, ← Nat.add_mul, Nat.mul_comm (a + b) b]_ = (a + b) * (a - b) := by rw [← Nat.sub_mul, Nat.mul_comm]
2.4 Http模块
2.4.1创建Http服务端
//1.导入http模块
let httprequire(http)//2.创建服务对象
let serverhttp.createServer((request,response)>{console.log(request.method) //获取请求方式console.log(request.url) //获取请求url(路径和参数部份)co…