Replace newlines with <p> paragraph and with <br /> tags

Question

So I know how to replace newlines in my C# code. But replacing a newline for a <br /> tag isn't always very correct.

So I was wondering what kind of strategy do others use? The correct way I guess would be to use <p> tags and <br /> tags.

Here are some examples of the results I would like to get.

If there is no newline I want the text to wrapped in a <p> tags.

This text contains no newlines

<p>This text contains no newlines</p>   

If the text contains a newline I want it to be replaced by a <br /> tag and be wrapped in <p> tags.

This text contains
1 newline

<p>This text contains<br /> 1 newline.</p>

If there are 'double newlines' I want that block to be wrapped in <p> tags.

This is a text with 'double newlines' at the end.

This is a text with no newline at the end.

<p>This a text with 'double newlines at the end.</p>
<p>This is a text with no newline at the end.</p>

I could write more examples/combination but I guess it's somewhat clear what I mean.

Thanks in advance.

Answer 1

Here's a way you could do it using only simple string replacements:

    string result = "<p>" + text
        .Replace(Environment.NewLine + Environment.NewLine, "</p><p>")
        .Replace(Environment.NewLine, "<br />")
        .Replace("</p><p>", "</p>" + Environment.NewLine + "<p>") + "</p>";

Note that your text must be HTML-escaped first otherwise you could be at risk of cross-site scripting attacks. (Note: even using <pre> tags still has a cross-site scripting risk).

Answer 2

You could just leave it alone and use CSS to render the breaks correctly. Here is a complicated example that is a kind of "pretty" replacement for the <pre> but you are using a <p> instead:

<p style="padding: 1em; line-height: 1.1em; font-family: monospace; white-space: pre; overflow: auto; background-color: rgb(240,255,240); border: thin solid rgb(255,220,255);">

Text goes here.

</p>