formatting string in MVC /C#

Question

I have a string 731478718861993983 and I want to get this 73-1478-7188-6199-3983 using C#. How can I format it like this ?

Thanks.

Could you describe the format more clearly and perhaps provide another example with a different number of digits - it looks like groups of 4 where possible, or does the first group need to be 2 digits? Also, check out this question which is very similar: stackoverflow.com/questions/5460962/… — Steve
– Steve, Commented Apr 1, 2011 at 10:59
possible duplicate of using string format for a credit card number — Steve
– Steve, Commented Apr 1, 2011 at 11:01

HABJAN · Accepted Answer · 2011-04-01 10:11:50Z

13

By using regex:

    public static string FormatTest1(string num)
    {
        string formatPattern = @"(\d{2})(\d{4})(\d{4})(\d{4})(\d{4})";
        return Regex.Replace(num, formatPattern, "$1-$2-$3-$4-$5");
    }

    // test
    string test = FormatTest1("731478718861993983");
    // test result: 73-1478-7188-6199-3983

answered Apr 1, 2011 at 10:11

HABJAN

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4 Comments

spender Over a year ago

So much better... I'm retiring my answer.

mathieu Over a year ago

If you have 1 problem and solve it by a regex, you now have 2 problems :)

Kobi Over a year ago

@mathieu - If you have a problem and apply aphorisms and dogmatic thinking, well, I'm not sure what you have then.

mathieu Over a year ago

@Kobi : codinghorror.com/blog/2008/06/…

Kobi · Accepted Answer · 2011-04-01 10:38:18Z

9

If you're dealing with a long number, you can use a NumberFormatInfo to format it:

First, define your NumberFormatInfo (you may want additional parameters, these are the basic 3):

NumberFormatInfo format = new NumberFormatInfo();
format.NumberGroupSeparator = "-";
format.NumberGroupSizes = new[] { 4 };
format.NumberDecimalDigits = 0;

Next, you can use it on your numbers:

long number = 731478718861993983;
string formatted = number.ToString("n", format);
Console.WriteLine(formatted);

After all, .Net has very good globalization support - you're better served using it!

edited Apr 1, 2011 at 10:38

answered Apr 1, 2011 at 10:24

Kobi

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3 Comments

Steve Over a year ago

The question was about a string, not a long, so it will need to be converted, as other answers spot.

Kobi Over a year ago

@Steve - I know, I actually ignored that part on purpose! I've added another answer for strings, and added this for number formatting. Either way, the OP should know how to convert the string, if that is needed, but that isn't the heart of the question.

Steve Over a year ago

True, but my pedantic comment does have a point, if the string was longer it may not be possible to parse in to a long, so a "pure" string based answer that does not require the conversion would be worth considering, although since your answer was accepted I guess that is not an issue anyway.

Yngve B-Nilsen · Accepted Answer · 2011-04-01 10:23:42Z

2

string s = "731478718861993983"
var newString = (string.Format("{0:##-####-####-####-####}", Convert.ToInt64(s));

answered Apr 1, 2011 at 10:23

Yngve B-Nilsen

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Comments

Anton Gogolev · Accepted Answer · 2011-04-01 10:16:27Z

1

LINQ-only one-liner:

var str = "731478718861993983";
var result = 
    new string(
        str.ToCharArray().
            Reverse(). // So that it will go over string right-to-left
            Select((c, i) => new { @char = c, group = i / 4}). // Keep group number
            Reverse(). // Restore original order
            GroupBy(t => t.group). // Now do the actual grouping
            Aggregate("", (s, grouping) => "-" + new string(
                grouping.
                    Select(gr => gr.@char).
                    ToArray())).
            ToArray()).
    Trim('-');

This can handle strings of arbitrary lenghs.

answered Apr 1, 2011 at 10:16

Anton Gogolev

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2 Comments

kenny Over a year ago

one liner....we have a different definition. just because you can put it on a line....

Anton Gogolev Over a year ago

@kenny: Purely as an exercise.

mathieu · Accepted Answer · 2011-04-01 10:18:14Z

1

Simple (and naive) extension method :

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("731478718861993983".InsertChar("-", 4));
    }
}

static class Ext
{
    public static string InsertChar(this string str, string c, int i)
    {
        for (int j = str.Length - i; j >= 0; j -= i)
        {
            str = str.Insert(j, c);
        }

        return str;
    }
}

answered Apr 1, 2011 at 10:18

mathieu

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Comments

Kobi · Accepted Answer · 2011-04-01 10:27:59Z

1

If you're dealing strictly with a string, you can make a simple Regex.Replace, to capture each group of 4 digits:

string str = "731478718861993983";
str = Regex.Replace(str, "(?!^).{4}", "-$0" ,RegexOptions.RightToLeft);
Console.WriteLine(str);

Note the use of RegexOptions.RightToLeft, to start capturing from the right (so "12345" will be replaced to 1-2345, and not -12345), and the use of (?!^) to avoid adding a dash in the beginning.
You may want to capture only digits - a possible pattern then may be @"\B\d{4}".

answered Apr 1, 2011 at 10:27

Kobi

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Comments

Eamonn McEvoy · Accepted Answer · 2011-04-01 10:13:15Z

0

string myString = 731478718861993983;
myString.Insert(2,"-");
myString.Insert(7,"-");
myString.Insert(13,"-");
myString.Insert(18,"-");

answered Apr 1, 2011 at 10:13

Eamonn McEvoy

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Comments

Stig-Rune Skansgård · Accepted Answer · 2011-04-01 10:15:19Z

0

My first thought is:

String s = "731478718861993983";
s = s.Insert(3,"-");
s = s.Insert(8,"-");
s = s.Insert(13,"-");
s = s.Insert(18,"-");

(don't remember if index is zero-based, in which case you should use my values -1) but there is probably some easier way to do this...

answered Apr 1, 2011 at 10:15

Stig-Rune Skansgård

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Comments

Gabriel · Accepted Answer · 2011-04-01 10:17:29Z

0

If the position of "-" is always the same then you can try

string s = "731478718861993983";
s = s.Insert(2, "-");
s = s.Insert(7, "-");
s = s.Insert(12, "-");
s = s.Insert(17, "-");

answered Apr 1, 2011 at 10:17

Gabriel

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SeeSharp · Accepted Answer · 2011-04-01 10:22:53Z

0

Here's how I'd do it; it'll only work if you're storing the numbers as something which isn't a string as they're not able to be used with format strings.

string numbers = "731478718861993983";
string formattedNumbers = String.Format("{0:##-####-####-####-####}", long.Parse(numbers));

Edit: amended code, since you said they were held as a string in your your original question

edited Apr 1, 2011 at 10:22

answered Apr 1, 2011 at 10:16

SeeSharp

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2 Comments

SeeSharp Over a year ago

Ah, yeah, I missed that. Give me a few minutes and I'll revise. Well spotted.

SeeSharp Over a year ago

@kenny I can obviously PadLeft() up to a length of 22, but that'll only work for a maximum of two leading zeros. Back to the drawing board!

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