Splitting text into lines with maximum length

algorithm, c#, string, text

Solution

Enjoy!

public static string SplitToLines(string text, char[] splitOnCharacters, int maxStringLength)
{
    var sb = new StringBuilder();
    var index = 0;

    while (text.Length > index)
    {
        // start a new line, unless we've just started
        if (index != 0)
            sb.AppendLine();

        // get the next substring, else the rest of the string if remainder is shorter than `maxStringLength`
        var splitAt = index + maxStringLength <= text.Length
            ? text.Substring(index, maxStringLength).LastIndexOfAny(splitOnCharacters)
            : text.Length - index;

        // if can't find split location, take `maxStringLength` characters
        splitAt = (splitAt == -1) ? maxStringLength : splitAt;

        // add result to collection & increment index
        sb.Append(text.Substring(index, splitAt).Trim());
        index += splitAt;
    }

    return sb.ToString();
}

Note that `splitOnCharacters` and `maxStringLength` could be saved in user settings area of the app.

Problem

I have a long string and I want to fit that in a small field. To achieve that, I break the string into lines on whitespace. The algorithm goes like this: ``` public static string BreakLine(string text, int maxCharsInLine) { int charsInLine = 0; StringBuilder builder = new StringBuilder(); for (int i = 0; i < text.Length; i++) { char c = text[i]; builder.Append(c); charsInLine++; if (charsInLine >= maxCharsInLine && char.IsWhiteSpace(c)) { builder.AppendLine(); charsInLine = 0; } } return builder.ToString(); } ``` But this breaks when there's a short word, followed by a longer word. "foo howcomputerwork" with a max length of 16 doesn't break, but I want it to. One thought I has was looking forward to see where the next whitespace occurs, but I'm not sure whether that would result in the fewest lines possible.

Original source