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import Foundation
/*
Week 135:
https://theweeklychallenge.org/blog/perl-weekly-challenge-135
Task #1: Middle 3-digits
You are given an integer.
Write a script find out the middle 3-digits of the given integer, if possible otherwise throw sensible error.
*/
enum ParamError: Error {
case missingNum
case invalidNum
case tooShort
case evenNumberOfDigits
}
do {
let paramCount:Int = Int(CommandLine.argc)
if paramCount <= 1 {
throw ParamError.missingNum
}
let num:String = CommandLine.arguments[1]
if isValid(num) {
let n:Int = abs(Int(num)!)
let s:String = String(n)
let l:Int = s.count
if l == 1 {
throw ParamError.tooShort
}
if l % 2 == 0 {
throw ParamError.evenNumberOfDigits
}
let i:Int = (l / 2) - 1
let str:String = String(n)
let start = str.index(str.startIndex, offsetBy: i)
let end = str.index(str.endIndex, offsetBy: 3 - (str.count-i))
let range = start..<end
print(str[range])
}
else {
throw ParamError.invalidNum
}
}
catch ParamError.missingNum {
print("Missing number.")
}
catch ParamError.invalidNum {
print("Invalid number.")
}
catch ParamError.tooShort {
print("Too short.")
}
catch ParamError.evenNumberOfDigits {
print("Even number of digits.")
}
catch let error {
print(error)
}
//
//
// Function
func isValid(_ num:String) -> Bool {
let pattern = "^\\-?\\d+$"
let regex = try! NSRegularExpression(pattern: pattern)
let range = NSRange(location: 0, length: num.utf16.count)
if regex.firstMatch(in: num, options: [], range: range) != nil {
return true
}
else {
return false
}
}
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