Replace consecutive characters with same single character

Question

Hi All,

I was just wondering if there is a simple way of doing this. i.e. Replacing the occurrence of consecutive characters with the same character.

For eg: - if my string is "something likeeeee tttthhiiissss" then my final output should be "something like this".

The string can contain special characters too including space.

Can you guys suggest some simple way for doing this.

Answer 1

How about:

s = new string(s
     .Select((x, i) => new { x, i })
     .Where(x => x.i == s.Length - 1 || s[x.i + 1] != x.x)
     .Select(x => x.x)
     .ToArray());

In english, we are creating a new string based on a char[] array. We construct that char[] array by applying a few LINQ operators:

1. Select: Capture the index i along with the current character x.
2. Filter out charaters that are not the same as the subsequent character
3. Select the character x.x back out of the anonymous type x.
4. Convert back to a char[] array so we can pass to constructor of string.

Answer 2

string myString = "something likeeeee tttthhiiissss";

char prevChar = '';
StringBuilder sb = new StringBuilder();
foreach (char chr in myString)
{
    if (chr != prevChar) {
        sb.Append(chr);
        prevChar = chr;
    }
}

Answer 3

This should do it:

var regex = new Regex("(.)\\1+");
var str = "something likeeeee!! tttthhiiissss";

Console.WriteLine(regex.Replace(str, "$1")); // something like! this

The regex will match any character (.) and \\1+ will match whatever was captured in the first group.