2 Multiply

8kyu Tantangan #2/366 - 16 Feb 2024

https://www.codewars.com/kata/50654ddff44f800200000004

2.1 Instruction

This code does not execute properly. Try to figure out why.

mul <- function(a, b) {
  a * c # try to figure out why it doesn't work!
}

2.2 YouTube Video

2.3 Solution Code

Karena argumen dari function mul() adalah a dan b sedangkan operasi perkalian di dalamnya menggunakan c yang belum diketahui dan tidak ada objek tersebut.

mul <- function(a, b) {
  a * c # try to figure out why it doesn't work!
}

Solusi: ganti objek c di dalam function mul() dengan b dari argumen function tersebut.

mul <- function(a, b) {
  a * b 
}

2.4 Test

library(testthat)

test_that("test for associativity of multiplication", {
  a <- runif(1, 0, 10000)
  b <- runif(1, 0, 10000)
  c <- runif(1, 0, 10000)
  expect_equal(mul(a, b), a * b)
  expect_equal(mul(mul(a, b), c), a * b * c)
  expect_equal(mul(a, mul(b, c)), a * b * c)
})

Test passed 😸

2.5 Supported by