Split and append a string?

Question

Right now I take in a string like this "112233 112233 112233 112233", and I split it into an array like this:

string text = ProcessString("112233 112233");
string[] dates = text.Split(' ');

And that works great, but I want to use string builder to build my string so they would end up like 11-22-33 11-22-33 etc.

So I did try this:

static string ProcessString(string input)
{
    StringBuilder buffer = new StringBuilder(input.Length * 3 / 2);

    for (int i = 0; i < input.Length; i++)
    {
        if ((i > 0) & (i % 2 == 0))
            buffer.Append("-");
        buffer.Append(input[i]);
    }
    return buffer.ToString();
}

It works, but it does not match the expected output of:

11-22-33 
11-22-33

My current output is:

11-22-33- 
1-12-23-3
-11-22-33

What can I do to fix this?

If there's only three elements, take it out of the for loop and use string.Format. string.Format("{0}-{1}-{2}", element1, element2, element3) — Ian P, Aug 12 '15 at 13:19
string text = "112233 112233 112233 112233"; string[] dates = text.Split(' ').Select(x => x.Substring(1,2) + "-" + x.Substring(2,2) + "-" + x.Substring(4, 2)).ToArray(); — jdweng, Aug 12 '15 at 13:23
@jdweng That really should be an answer instead of a comment. — juharr, Aug 12 '15 at 13:25
@IanP the 3 strings were just there because I wanted to test, I don't want to hard code the values really. — Foo Bar, Aug 12 '15 at 13:26

poke · Accepted Answer · 2015-08-12T13:36:43.473

You can process a single string simply by iterating and collecting size-2 substrings of the string, and then joining them by the - character:

string s = "112233";

List<string> parts = new List<string>(s.Length / 2);
for (int i = 0; i < s.Length; i += 2)
    parts.Add(s.Substring(i, 2));

Console.WriteLine(string.Join("-", parts)); // 11-22-33

So, for your full problem, you could do this:

static string ProcessString(string input)
{
    var segments = input.Split(' ').Select(s =>
    {
        List<string> parts = new List<string>(s.Length / 2);
        for (int i = 0; i < s.Length; i += 2)
            parts.Add(s.Substring(i, 2));
        return string.Join("-", parts);
    });

    return string.Join(" ", segments);
}

score 1 · Answer 2 · edited May 23 '17 at 12:14

Can i offer you another Regex + LINQ approach?

var newDates = dates.Select(d => Regex.Replace(d, ".{2}", "$0-").Trim('-'));
string result = string.Join(" ", newDates);

But i like this extension more because it's readable and re-usable:

public static IEnumerable<String> SplitInParts(this String s, Int32 partLength)
{
    if (s == null)
        throw new ArgumentNullException("s");
    if (partLength <= 0)
        throw new ArgumentException("Part length has to be positive.", "partLength");

    for (var i = 0; i < s.Length; i += partLength)
        yield return s.Substring(i, Math.Min(partLength, s.Length - i));
}

Then the code is even easier:

var newDates = dates.Select(d => string.Join("-", d.SplitInParts(2)));
string result = string.Join(" ", newDates);

score 1 · Answer 3 · answered Aug 12 '15 at 13:32

1

How about regex:

string s = "112233";
string pattern = @"\d{2}\B";
string result = Regex.Replace(s, pattern, m => m.Value + "-");

answered Aug 12 '15 at 13:32

Alexander Petrov

13,457
2
20
49

I like this solution; it also works for the original string `"112233 112233"`. – poke Aug 12 '15 at 13:38

score 0 · Answer 4 · answered Aug 12 '15 at 13:38

I have this approach :

       string input = "112233 445566 778899 101010";
       string[] dates = input.Split(' ');

       foreach (string date in dates){
           Console.WriteLine(date);
           string result = date.Substring(0, 2) + '-' + date.Substring(2, 2) + "-" + date.Substring(4, 2);
           Console.WriteLine(result);
       }

score 0 · Answer 5 · answered Aug 12 '15 at 13:41

0

You can use Array.ConvertAll:

string str = "112233 112233 112233 112233";
string[] dates = str.Split();

dates = Array.ConvertAll(dates, s => s.Insert(4, "-").Insert(2, "-"));

foreach (var s in dates)
    Console.WriteLine(s);

answered Aug 12 '15 at 13:41

w.b

11,026
5
30
49

Split and append a string?

5 Answers5