Elixir-带参数的混合运行示例

Question

Elixir is powered by Erlang OTP, which uses Mix as a build tool for creating and running applications.

I am now learning elixir as a beginner

I can create a mix application from command line by specifying mix new sample and I write some code in this to learn the basics of elixir and mix.

exs and ex file could be run by using the command mix run sample.exs

I am trying to write a code to get a specific type of number ,say prime numbers between a particular range (100000,20000)

I want to give the two numbers (100000,200000) as arguments to the mix run command like mix run sample.exs 100000,200000 and get the result in the given range.

Note - I dont want to build and executable using escript and need to use only the mix run command and also not mix run -e

How to get the args as input values in the exs file ?

Thanks a lot

Answer 1

While System.argv/0 somewhat works in trivial cases, we usually use OptionParser for more or less sophisticated options processing.

["--start", "0", "--end", "42"]
|> OptionParser.parse(
  strict: [start: :integer, end: :integer]
)
|> IO.inspect()
#⇒ {[start: 0, end: 42], [], []}

To use these values:

{args, _, _} =
  OptionParser.parse(
    ["--start", "0", "--end", "42"],
    strict: [start: :integer, end: :integer]
  )
Enum.each(args[:start]..args[:end], &IO.inspect/1)

Answer 2

In order to get the arguments that were passed to your program, you need to use System.argv() . For example, given the following exs script:

args = System.argv()  
       |> IO.inspect()

and running elixir so_exs.exs input_1 input_2 (note I don't have a Mix project here so I am not using mix run ) you get the following. The args variable now contains a list of all the arguments passed to the program:

["input_1", "input_2"]