c# Regex Split Binary String

Question

I'm trying to split a string of binary digits in a specific way

Let's say this is my string 100011001110010101110

I want to split the string at every 0 before a 1

So the string above after split becomes

1000 1100 11100 10 10 1110

I used the Regex pattern /(1+0+)/g which splits the string properly, but it misses some groups. Here is the c# code

Regex.Split(stringToSplit, @"(1+0+)");

Please what am i getting wrong.

EDIT: I failed to mention that I am certain a 1 will always precede a 0

Thanks in advance.

Dmitrii Bychenko · Accepted Answer · 2020-01-22 08:48:04Z

6

You can try looking ahead and behind, i.e. spilt on zero-length text with 0 behind the split and 1 ahead it

Code:

  string source = "100011001110010101110";

  var result = Regex.Split(source, "(?<=0)(?=1)");

  // Let's have a look
  Console.Write(string.Join(Environment.NewLine, result));

Outcome:

Edit: Pattern (?<=0)(?=1) explanation:

(?<=0) - 0 should be behind the split
       - empty; split on epmty (zero-length) text
(?=1)  - 1 should be ahead of the split

So we have

1000 110011
   ^^^
   |||- 1 should be ahead of split
   ||--   split here
   |--- 0 should be behind the split

edited Jan 22, 2020 at 8:48

answered Jan 21, 2020 at 9:03

Dmitrii Bychenko

188k20 gold badges178 silver badges231 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Tân Over a year ago

Nice! Can you please add more explanation about the pattern?

Travis Sowoolu Over a year ago

This works like a charm. No extra processing, you get the exact results you need.

Innat3 · Accepted Answer · 2020-01-21 09:05:05Z

1

Problem is your Regex Pattern returns several Matches as you can see Here.

You could retrieve the values using .Matches() instead.

Regex.Matches("100011001110010101110", "(1+0+)").Cast<Match>().Select(x => x.Value);

answered Jan 21, 2020 at 9:05

Innat3

3,5762 gold badges15 silver badges30 bronze badges

2 Comments

Wiktor Stribiżew Over a year ago

You will lose any leading zeros or trailing ones if present.

Travis Sowoolu Over a year ago

This works but it seems the Cast and Select increases execution time. Thanks for the response.

Jeevitha · Accepted Answer · 2020-01-21 09:40:20Z

0

Code:

var input = "100011001110010101110";
var results = Regex.Split(input, @"(1+0+)")
                        .Where(n => !string.IsNullOrEmpty(n))
                        .ToList();
Console.WriteLine(string.Join("\n", results));

Outcome:

1000
1100
11100
10
10
1110
Press any key to continue . . .

answered Jan 21, 2020 at 9:40

Jeevitha

1179 bronze badges

Collectives™ on Stack Overflow

c# Regex Split Binary String

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related