Using regular expressions to validate a numeric range

Question

My input number is an int. But the input number must be in a range from -2055 to 2055 and I want to check this by using regular expression.

So is there anyway to wri

Answer 1

So many answers, but noone reads (or cares) about the OPs side question in the comments?

I'm writing an interpreter in OCaml .... how can i validate the input number within the range without using regex ?? – Trung Nguyen Mar 2 at 17:30

As so many answers - correctly - pointed out that using regex is horrible for this scenario, lets think about other ways in OCaml! It is a while since I used OCaml, but with looking up a few constructs I was able to knock this together:

let isInRange i = 
    not(i < -2055 or i > 2055);;

let isIntAndInRange s = 
    try
    let i = int_of_string s in
    not(i < -2055 or i > 2055)
    with Failure "int_of_string" -> false;;

let () = print_string "type a number: " in
let s = read_line () in
isIntAndInRange s

If anything about is unclear, please read up on its syntax, type conversion functions and exception handling and input-output functions.

The user input part is only used to demonstrate. It might be more convenient to use the read_int function there. But the basic concept of handling the exception stays the same.