CODEWITHSUNDEEP
c#stringoptimizationsplit
Andrew
Andrew

Reputation: 7778

the most efficient way to separate string

I have this string:

"B82V16814133260"

what would be the most efficient way to get two strings out of it:

left part String: "B82V" rigth part string: "16814133260"

The rule is this: take all numbers on the right side and create string out of them, then take the reminder and place it into another string.

This is my solution, but it is too bulky! How to do it short and efficient?

        String leftString = "";
        String rightString="";

        foreach (char A in textBox13.Text.Reverse())
        {
            if (Char.IsNumber(A))
            {
                rightString += A;
            }
            else
            {
                break;
            }
        }

        char[] arr = rightString.ToArray();
        Array.Reverse(arr);

        rightString=new string(arr);
        leftString = textBox13.Text.Replace(rightString, "");

Upvotes: 7

Views: 375

Answers (6)

mowwwalker
mowwwalker

Reputation: 17362

Well, the other answer is probably better, but I wrote this anyway, so I'm posting it:

Needs:

using System.Text.RegularExpressions;

Code: 

string str = "B82V16814133260";
string[] match = Regex.match(str, @"^([\d\w]+?\w)(\d+)$").Groups;
string left = match[1];
string right = match[2];

Upvotes: 5

payo
payo

Reputation: 4561

I read 'most efficient' as 'fastest'.

I wrote a quick test with a long string, running 10 million times.

Austin's solution to use TrimEnd ran in 4.649s

My solution ran in 1.927 seconds

    int j = given.Length - 1;

    for (; j >= 0; j--)
    {
      char c = given[j];
      if (c < '0' || c > '9')
      {
        break;
      }
    }

    var first = given.Substring(0, j + 1);
    var rest = given.Substring(j + 1);

Note that my builds were not debug (in debug, my solution is slower, but that is because TrimEnd is not running in debug bits). So, if you are running my code in your application, and are building debug, it'll be slower.

Upvotes: 2

Aheho
Aheho

Reputation: 12821

 string Source = textBox13.Text;

 for (i = Source.Length - 1; i >=0; i--)
 {
      if (! Char.IsNumber(Source[i])
         break;
 }

 string leftString = Source.Left(i+1);
 string rightString = Source.Right(i+1,Source.Length-i-1);

Upvotes: 0

Austin Salonen
Austin Salonen

Reputation: 50225

This yields what you're expecting:

var given = "B82V16814133260";
var first = given.TrimEnd("0123456789".ToCharArray());
var rest = given.Substring(first.Length);

Console.Write("{0} -> {1} -- {2}", given, first, rest);
//  B82V16814133260 -> B82V -- 16814133260

Upvotes: 14

captncraig
captncraig

Reputation: 23088

I like linq.

    var s = "B82V16814133260";
    var lastNonNumeric = s.Reverse().Where(x => !char.IsDigit(x)).FirstOrDefault();
    var index = s.LastIndexOf(lastNonNumeric);
    var secondString = s.Substring(index + 1);
    var firstString = s.Substring(0, index+1);

Probably not the best or most robust solution, but it works for your test string.

Upvotes: 1

Balazs Tihanyi
Balazs Tihanyi

Reputation: 6719

This should be very fast:

int index = text.Length - 1;
while (index >= 0 && Char.IsDigit(text[index]))
{
    index--;
}
string left = text.Substring(0, index + 1);
string right = text.Substring(index + 1);

Upvotes: 3

Related Questions