Question

I have a large string separated by newline character. This string contains 100 lines. I want to split these line into small chunks say chunk of 20 also based on newline character.

Let’s say the string variable is like this,

Line1
This is line2
Line3 is here
I am Line4

Now I want to split this large string variable into small chunks of 2. The result should be 2 strings as,

Line1
This is line2

---

Line3 is here
I am Line4

Using Split function, I am not getting the expected results. Please help me in achieving this.

Thanks in advance,

Vijay

Answer 1

The simple approach (Split on Environment.NewLine, then loop and append):

public static List<string> GetStringSegments(string originalString, int linesPerSegment)
{

    List<string> segments = new List<string>();
    string[] allLines = originalString.Split(new string[] {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries); 
    StringBuilder sb = new StringBuilder();

    int linesProcessed = 0;
    for (int i = 0; i < allLines.Length; i++)
    {
        sb.AppendLine(allLines[i]);
        linesProcessed++;

        if (linesProcessed == linesPerSegment
            || i == allLines.Length-1)
        {
            segments.Add(sb.ToString());
            sb.Clear();
            inesProcessed = 0;
        }
    }

    return segments;
}

The above approach is slightly inefficient since it requires splitting the string first into individual lines, which creates unnecessary strings. A string of 1000 lines will create an array of 1000 strings. We can improved this if we just scan the string and search for \n:

public static List<string> GetStringSegments(string original, int linesPerSegment)
{
    List<string> segments = new List<string>();

    int startIndex = 0;
    int newLinesEncountered = 0;

    for (int i = 0; i < original.Length; i++)
    {
        if (original[i] == '\n')
        {
            newLinesEncountered++;
        }

        if (newLinesEncountered == linesPerSegment
            || i == original.Length - 1)
        {
            segments.Add(original.Substring(startIndex, (i - startIndex + 1)));
            startIndex = i + 1;
            newLinesEncountered = 0;
        }
    }

    return segments;
}