Split a string containing 16 digits into 4 groups

If you take a look at the plastic in your wallet the 16 digit credit card number is broken into 4 groups of 4. Im trying to do the same thing,

Currently I have a string that has 16 digits but is formed as 1 single number. How can I add a "开发者_如何学Go " after the 4th 8th & 12th number?

Any tips would be really helpful.

Thanks

var number = 1234567890123456;
number.ToString( "0000-0000-0000-0000" );

Try something similar to this answer, using a NumberFormatInfo:

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

Use as:

long number = 7314787188619939;
string formatted = number.ToString("n", format);
Console.WriteLine(formatted);

Or, if you're dealing with a string, you may choose can use a regex for a quick string manipulation. This will be easy to adapt to other characters:

string str = "7314787188619939";
str = Regex.Replace(str, "(?!^).{4}", " $0" ,RegexOptions.RightToLeft);

string number = "1234567890ABCDEF";
int counter = 0;
var result = number
    .GroupBy(_ => counter++ / 4)
    .Select(g => new String(g.ToArray()));

There are many answers. Given a string s=1234567890123456 the easiest might be to create a StringBuilder and append it. Untested code example below.

StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.Length; i += 4)
{
      sb.append(s.Substring(i, 4)); // Append these 4
      if (i != s.Length - 4)
          sb.append(" "); // append a space for all but the last group
}
Console.WriteLine(sb.ToString());

You may try something like this, an extension method

    public static IEnumerable<String> SplitToParts(this String forSplit, Int32 splitLength) 
    {   
        for (var i = 0; i < forSplit.Length; i += splitLength)
          yield return forSplit.Substring(i, Math.Min(splitLength, forSplit.Length - i));
    }
string s ="1234123412341234";

s.SplitToParts(4) should do the trick

Hope this works !

Or if working with MD5 hashes, you could use an implementation like so...

       public string exHashMd5(string data)
    {

            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
            md5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(data));
            byte[] result = md5.Hash;
            StringBuilder str = new StringBuilder();
            for (int i = 0; i < result.Length; i++)
            {
                str.Append(result[i].ToString("X2"));
            }

 /// The implementation like so. (Below) 

            NumberFormatInfo format = new NumberFormatInfo();
            format.NumberGroupSeparator = " ";
            format.NumberGroupSizes = new[] { 8 };
            format.NumberDecimalDigits = 0;
            string rstr = str.ToString();
            rstr = Regex.Replace(rstr, "(?!^).{8}", " $0", RegexOptions.RightToLeft);
            return rstr.ToString();

 /// At the end you get yourself a nice 4 way split.
 /// Test it out. have a go with chucking it into a 
 /// MessageBox.Show(exHashMd5("yourstring"));

    }

 /// Could even go one further and add
     string hashtext;
     string newline = Enviroment.Newline;
     hashtext = exHashMd5("yourtext");
/// Then you do a simple command.
    MessageBox.Show(hashtext + newline + hashtext); 
/// Nice four way again. complex but yet made simple.

To work out what you need it to do, use maths. seriously, its mathematical. divide the amount of characters, till you are able to get a sum that equals four. for example, 32 / 8 = 4. then this will give you the four way split you need. basic maths. basic. basic. basic.