Split string and string arrays

Question

string s= abc**xy**efg**xy**ijk123**xy**lmxno**xy**opq**xy**rstz;

I want the output as string array, where it get splits at "xy". I used

  string[] lines = Regex.Split(s, "xy"); 

here it removes xy . I want array along with xy . So, after I split my string to string array, array should be as below.

lines[0]= abc;
lines[1]= xyefg;
lines[2]= xyijk123;
lines[3]= xylmxno;
lines[4]= xyopq ;
lines[5]= xyrstz;

how can i do this?

Answer 1

(?=xy)

You need to split on 0 width assertion .See demo.

https://regex101.com/r/fM9lY3/50

string strRegex = @"(?=xy)";
Regex myRegex = new Regex(strRegex, RegexOptions.None);
string strTargetString = @"abcxyefgxyijk123xylmxnoxyopqxyrstz";

return myRegex.Split(strTargetString);

Output:

abc xyefg xyijk123 xylmxno xyopq xyrstz

Answer 2

If you're not married to Regex, you could make your own extension method:

public static IEnumerable<string> Ssplit(this string InputString, string Delimiter)
{
    int idx = InputString.IndexOf(Delimiter);
    while (idx != -1)
    {
        yield return InputString.Substring(0, idx);
        InputString = InputString.Substring(idx);

        idx = InputString.IndexOf(Delimiter, Delimiter.Length);
    }

    yield return InputString;
}

Usage:

string s = "abc**xy**efg**xy**ijk123**xy**lmxno**xy**opq**xy**rstz";
var x = s.Ssplit("xy");

Answer 3

It seems fairly simple to do this:

string s = "abc**xy**efg**xy**ijk123**xy**lmxno**xy**opq**xy**rstz";

string[] lines = Regex.Split(s, "xy");

lines = lines.Take(1).Concat(lines.Skip(1).Select(l => "xy" + l)).ToArray();

I get the following result:

I don't know if you wanted to keep the ** - your question doesn't make it clear. Changing the RegEx to @"\\*\\*xy\\*\\*" will remove the ** .

Answer 4

How about simply looping throgh the array starting with index 1 and adding the "xy" string to each entry?

Alternatively implement your own version of split that cuts the string how you want it.

Yeat another solution would be matching "xy*" in a non-greedy way and your array would be the list of all matches. Depending on language this probably won't be called split BTW.