How to separate character and number part from string

Question

E.g., I would like to separate:

OS234 to OS and 234
AA4230 to AA and 4230

I have used following trivial solution, but I am quite sure that there should be a more efficient and robust solution .

private void demo()
    {   string cell="ABCD4321";
        int a = getIndexofNumber(cell);
        string Numberpart = cell.Substring(a, cell.Length - a);
        row = Convert.ToInt32(rowpart);
        string Stringpart = cell.Substring(0, a);
    }

private int getIndexofNumber(string cell)
        {
            int a = -1, indexofNum = 10000;
            a = cell.IndexOf("0"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("1"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("2"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("3"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("4"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("5"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("6"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("7"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("8"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }
            a = cell.IndexOf("9"); if (a > -1) { if (indexofNum > a) { indexofNum = a; } }

            if (indexofNum != 10000)
            { return indexofNum; }
            else
            { return 0; }


        }

score 35 · Answer 1 · edited Sep 05 '14 at 17:00

35

Regular Expressions are best suited for this kind of work:

using System.Text.RegularExpressions;

Regex re = new Regex(@"([a-zA-Z]+)(\d+)");
Match result = re.Match(input);

string alphaPart = result.Groups[1].Value;
string numberPart = result.Groups[2].Value;

edited Sep 05 '14 at 17:00

JHowIX

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answered Dec 28 '09 at 05:08

x0n

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Might want to add two lines to this answer: string alphaPart = result.Groups[1]; string numberPart = result.Groups[2]; – Brett Daniel Dec 28 '09 at 05:16
Following seems to be more complete solution: Regex re = new Regex(@"([a-zA-Z]+)(\d+)"); Match result = re.Match("as23"); string alphaPart = result.Groups[1].ToString (); string numberPart = result.Groups[2].ToString(); – Thunder Dec 28 '09 at 05:17
2

Isn't it `result.Groups[1].Value`? – Dmitri Nesteruk Dec 28 '09 at 06:02
result.Groups[2].ToString(); Worked for me Further we should add Imports Systems.Text.Regularexpression @ top. – Thunder Dec 28 '09 at 08:41
"GJ10HE1895" is my string any i want it like GJ,10,HE, 1895 seperately in different group can you suggest solution. @x0n – Ankit Mori Mar 13 '19 at 13:22

score 13 · Answer 2 · answered Dec 28 '09 at 05:08

13

Use Linq to do this

string str = "OS234";

var digits = from c in str
             select c
             where Char.IsDigit(c);

var alphas = from c in str
             select c
             where !Char.IsDigit(c);

answered Dec 28 '09 at 05:08

this. __curious_geek

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4

This seems to be good solution ,but unfortunately .net 2.0 users could not use Linq – Thunder Dec 28 '09 at 05:12
5

I recomend - upgrade to C# 3.0. – this. __curious_geek Dec 29 '09 at 06:12

score 6 · Answer 3 · edited Jun 06 '12 at 19:36

6

Everyone and their mother will give you a solution using regex, so here's one that is not:

 // s is string of form ([A-Za-z])*([0-9])* ; char added
 int index = s.IndexOfAny(new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' });
 string chars = s.Substring(0, index);
 int num = Int32.Parse(s.Substring(index));

edited Jun 06 '12 at 19:36

UNeverNo

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answered Dec 28 '09 at 05:10

jason

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2

You got regex problems? I feel bad for you son. I got 99 problems but a Regex ain't one. – Captain Kenpachi Feb 24 '21 at 10:43

aloisdg · Answer 4 · 2021-08-24T15:22:53.410

I really like jason's answer. Lets improve it a bit. We dont need regex here. My solution handle input like "H1N1":

public static IEnumerable<string> SplitAlpha(string input)
{
    var words = new List<string> { string.Empty };
    for (var i = 0; i < input.Length; i++)
    {
        words[words.Count-1] += input[i];
        if (i + 1 < input.Length && char.IsLetter(input[i]) != char.IsLetter(input[i + 1]))
        {
            words.Add(string.Empty);
        }
    }
    return words;
}

This solution is linear O(n).

output

"H1N1" -> ["H", "1", "N", "1"]
"H" -> ["H"]
"GH1N12" -> ["GH", "1", "N", "12"]
"OS234" -> ["OS", "234"]

Same solution with a StringBuilder

public static IEnumerable<string> SplitAlpha(string input)
{
    var words = new List<StringBuilder>{new StringBuilder()};
    for (var i = 0; i < input.Length; i++)
    {
        words[words.Count - 1].Append(input[i]);
        if (i + 1 < input.Length && char.IsLetter(input[i]) != char.IsLetter(input[i + 1]))
        {
            words.Add(new StringBuilder());
        }
    }

    return words.Select(x => x.ToString());
}

Try it Online!

@DJBurb Glad I could be useful :) – aloisdg Mar 23 '18 at 14:48 — aloisdg, Mar 23 '18 at 14:48

score 4 · Answer 5 · answered Aug 17 '16 at 15:53

If you want resolve more occurrences of char followed by number or vice versa you can use

private string SplitCharsAndNums(string text)
{
    var sb = new StringBuilder();
    for (var i = 0; i < text.Length - 1; i++)
    {
        if ((char.IsLetter(text[i]) && char.IsDigit(text[i+1])) ||
            (char.IsDigit(text[i]) && char.IsLetter(text[i+1])))
        {
            sb.Append(text[i]);
            sb.Append(" ");
        }
        else
        {
            sb.Append(text[i]);
        }
    }

    sb.Append(text[text.Length-1]);

    return sb.ToString();
}

And then

var text = SplitCharsAndNums("asd1 asas4gr5 6ssfd");
var tokens = text.Split(' ');

Works well until you meet a non-letter or numeric, such as a . in a file name. Change char.IsLetter to !char.IsNumeric — Tod, Jan 18 '19 at 10:28

score 1 · Answer 6 · answered Dec 28 '09 at 05:13

Are you doing this for sorting purposes? If so, keep in mind that Regex can kill performance for large lists. I frequently use an AlphanumComparer that's a general solution to this problem (can handle any sequence of letters and numbers in any order). I believe that I adapted it from this page.

Even if you're not sorting on it, using the character-by-character approach (if you have variable lengths) or simple substring/parse (if they're fixed) will be a lot more efficient and easier to test than a Regex.

bniwredyc · Answer 7 · 2009-12-28T06:41:12.497

.NET 2.0 compatible, without regex

public class Result
{
    private string _StringPart;
    public string StringPart
    {
        get { return _StringPart; }
    }

    private int _IntPart;
    public int IntPart
    {
        get { return _IntPart; }
    }

    public Result(string stringPart, int intPart)
    {
        _StringPart = stringPart;
        _IntPart = intPart;
    }
}

class Program
{
    public static Result GetResult(string source)
    {
        string stringPart = String.Empty;
        int intPart;
        var buffer = new StringBuilder();
        foreach (char c in source)
        {
            if (Char.IsDigit(c))
            {
               if (stringPart == String.Empty)
               {
                    stringPart = buffer.ToString();
                    buffer.Remove(0, buffer.Length);
                }
            }

            buffer.Append(c);
        }

        if (!int.TryParse(buffer.ToString(), out intPart))
        {
            return null;
        }

        return new Result(stringPart, intPart); 
    }

    static void Main(string[] args)
    {
        Result result = GetResult("OS234");
        Console.WriteLine("String part: {0} int part: {1}", result.StringPart, result.IntPart);
        result = GetResult("AA4230 ");
        Console.WriteLine("String part: {0} int part: {1}", result.StringPart, result.IntPart);
        result = GetResult("ABCD4321");
        Console.WriteLine("String part: {0} int part: {1}", result.StringPart, result.IntPart);
        Console.ReadKey();
    }
}

@this.__curious_geek yep. I like Jasons solution. – bniwredyc Dec 28 '09 at 06:40 — bniwredyc, Dec 28 '09 at 06:40

score 1 · Accepted Answer · answered Dec 28 '09 at 05:40

I have used bniwredyc's answer to get Improved version of my routine:

    private void demo()
        {
            string cell = "ABCD4321";
            int row, a = getIndexofNumber(cell);
            string Numberpart = cell.Substring(a, cell.Length - a);
            row = Convert.ToInt32(Numberpart);
            string Stringpart = cell.Substring(0, a);
        }

        private int getIndexofNumber(string cell)
        {
            int indexofNum=-1;
            foreach (char c in cell)
            {
                indexofNum++;
                if (Char.IsDigit(c))
                {
                    return indexofNum;
                }
             }
            return indexofNum;
        }

Karshanguna R · Answer 9 · 2018-10-01T14:38:43.070

-2

Just use the substring function and set position inside the bracket.

 String id = "DON123";
 System.out.println("Id nubmer is : "+id.substring(3,6));

Answer:

 Id number is: 123

edited Oct 01 '18 at 14:38

answered Oct 01 '18 at 14:05

Karshanguna R

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2

1

The string is not the same length each time, nor the number of characters or digits – Captain Kenpachi Feb 24 '21 at 10:42

score -3 · Answer 10 · edited Mar 18 '16 at 12:13

-3

use Split to seprate string from sting that use tab \t and space

string s = "sometext\tsometext\tsometext";
string[] split = s.Split('\t');

now you have an array of string that you want too easy

edited Mar 18 '16 at 12:13

Slava Vedenin

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answered Mar 18 '16 at 11:48

Amir Lavaie

1

this answer is irrelevant to the question, it's not about separating number from letters at all. also your "too easy" in the end sounds spiteful, author wouldn't ask question if that was as easy as this answer states – Andrew Feb 19 '23 at 16:23

How to separate character and number part from string

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