regex - Convert a string to an array of strings in c#

Question

Can I get an array of string with CRLF or LF or CR included, only with linq ? I don't want to use a loop . I have a string like this "Hello Stackverflow How are you doing ", and i have to convert it to be like this

mystring[0] = "Hello 
"
mystring[1] = "Stackverflow
"
mystring[2] = "How are you doing 
"

Any ideas ?

question from:https://stackoverflow.com/questions/66060859/convert-a-string-to-an-array-of-strings-in-c-sharp

Answer 1

This is slightly complicated by the fact that we have to handle " ", " " AND " ". I'm assuming you don't need to handle " " - if you do, you'll have to add a case for it in the code below.

Obviously there are many ways to solve this; here's a low-level approach that doesn't use anything other than a basic loop:

public static IEnumerable<string> SplitByAndKeepLineSeparators(string input)
{
    if (input.Length == 0)
        yield break;

    int i = 0, j = 0;

    while (true)
    {
        if (i == input.Length - 1) // Last char?
        {
            yield return input.Substring(j, i - j + 1);
            break;
        }

        switch (input[i])
        {
            case '
' when input[i+1] == '
':
                yield return input.Substring(j, i - j + 2);
                i += 2;
                j =  i;
                break;

            case '
':
                yield return input.Substring(j, i - j + 1);
                j = ++i;
                break;

            case '
':
                yield return input.Substring(j, i - j + 1);
                j = ++i;
                break;

            default:
                ++i;
                break;
        }
    }
}

Note: If using an older version of C# you won't be able to use that kind of switch, so your code would have to be:

public static IEnumerable<string> SplitByAndKeepLineSeparators(string input)
{
    if (input.Length == 0)
        yield break;

    int i = 0, j = 0;

    while (true)
    {
        if (i == input.Length - 1) // Last char?
        {
            yield return input.Substring(j, i - j + 1);
            break;
        }

        if (input[i] == '
' && input[i + 1] == '
')
        {
            yield return input.Substring(j, i - j + 2);
            i += 2;
            j =  i;
        }
        else if (input[i] == '
')
        {
            yield return input.Substring(j, i - j + 1);
            j = ++i;
        }
        else if (input[i] == '
')
        {
            yield return input.Substring(j, i - j + 1);
            j = ++i;
        }
        else
        {
            ++i;
        }
    }
}