if...else... 조건문 사용 예제 for OCaml

소스 파일명: testIf.ml

1. (*
2.    Filename: testIf.ml
4.    Execute: ocaml testIf.ml -8e-2
6.      Or
8.    Compile: ocamlc -o testIf.ml
9.    Execute: ./testIf -8e-2
11.      Or
13.    Compile: ocamlc -o testIf.exe testIf.ml
14.    Execute: testIf -8e-2
15.    Date: 2013. 1. 26.
16.    Copyright (c) pkim _AT_ scripts.pe.kr
17. *)
20. let printUsing() =
21.      Printf.printf "Using: testIf [number]\n";
22.      Printf.printf "   or  ./testIf [number]\n";
23.      Printf.printf "   or  ocaml testIf.ml [number]\n";
24.      Printf.printf "This determines whether the number is positive or not.\n";;
26. let isPositve = function
27.      | x when x > 0.0 -> "positive";
28.      | x when x < 0.0 -> "negative" ;
29.      | x when x = 0.0 -> "zero" ;
30.      | _ -> "not a floating number";;
32. let main () =
33.     print_int(Array.length Sys.argv);;
34.     if ((Array.length Sys.argv) < 2) then
35.         printUsing()
36.     else
37.         let arg = float_of_string Sys.argv.(1) in
38.         let msg = isPositve(arg) in
39.         Printf.printf "%g is %s." arg msg;
40.         print_newline();;
41.     exit 0;;
43. main ();;
    

컴파일> ocamlc -o testIf.exe testIf.ml

실행> testIf -1.2
-1.2 is negative.

실행> testIf 0.0
0 is zero.


실행> testIf -0.1e-127
-1e-128 is negative.