Simple text to HTML conversion

Question

I have a very simple asp:textbox with the multiline attribute enabled. I then accept just text, with no markup, from the textbox. Is there a comm

Answer 1

Combining all previous plus considering titles and subtitles within the text comes up with this:

public static string ToHtml(this string text)
{
    var sb = new StringBuilder();

    var sr = new StringReader(text);
    var str = sr.ReadLine();
    while (str != null)
    {
        str = str.TrimEnd();
        str.Replace("  ", "  ");
        if (str.Length > 80)
        {
            sb.AppendLine($"
{str}
");
        }
        else if (str.Length > 0)
        {
            sb.AppendLine($"{str}
");
        }
        str = sr.ReadLine();
    }

    return sb.ToString();
}

the snippet could be enhanced by defining rules for short strings