using System;

using System.Collections.Generic;

using System.Linq;

using System.Diagnostics;

​

IEnumerable<char> GetCharsFromAscii(int start, int count)

{

    return Enumerable.Range(start, count).Select(x => (char)x);

}

​

IEnumerable<char> GetSpaceAndPunctuactionMarks()

{

    var punctuactionMarks = new List<char>();

    var ranges = new List<(int Start, int Count)> { (32, 16), (58, 7), (91, 6), (123, 4) };

    ranges.ForEach(range => punctuactionMarks.AddRange(GetCharsFromAscii(range.Start, range.Count)));

    return punctuactionMarks;

}

​

string CreateSearchPhrase(string oldPhrase)

{

    var time = new Stopwatch();

    time.Start();

    var separators = GetSpaceAndPunctuactionMarks().ToArray();

    var words = oldPhrase.Split(separators).Where(word => word != "");

    var newPhrase = string.Join(" ", words);

    Console.WriteLine(time.Elapsed);

    return string.Join("", "*", newPhrase, "*");

}

​

Console.WriteLine(CreateSearchPhrase("asdf ! asdf asdfasdf asdfasdf asdfasdf    sadfasdf !asdf -+asdf ! asdf asdfasdf asdfasdf asdfasdf    sadfasdf !asdf -+"));