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php – New line to paragraph function

Posted by: admin April 23, 2020 Leave a comment

Questions:

I have this interesting function that I’m using to create new lines into paragraphs. I’m using it instead of the nl2br() function, as it outputs better formatted text.

function nl2p($string, $line_breaks = true, $xml = true) {

$string = str_replace(array('<p>', '</p>', '<br>', '<br />'), '', $string);

// It is conceivable that people might still want single line-breaks
// without breaking into a new paragraph.
if ($line_breaks == true)
    return '<p>'.preg_replace(array("/([\n]{2,})/i", "/([^>])\n([^<])/i"), array("</p>\n<p>", '<br'.($xml == true ? ' /' : '').'>'), trim($string)).'</p>';
else 
    return '<p>'.preg_replace(
    array("/([\n]{2,})/i", "/([\r\n]{3,})/i","/([^>])\n([^<])/i"),
    array("</p>\n<p>", "</p>\n<p>", '<br'.($xml == true ? ' /' : '').'>'),

    trim($string)).'</p>'; 

}

The problem is that whenever I try to create a single line break, it inadvertently removes the first character of the paragraph below it. I’m not familiar enough with regex to understand what is causing the problem.

How to&Answers:

The problem is with your match for single line breaks. It matches the last character before the line break and the first after. Then you replace the match with <br>, so you lose those characters as well. You need to keep them in the replacement.

Try this:

function nl2p($string, $line_breaks = true, $xml = true) {

$string = str_replace(array('<p>', '</p>', '<br>', '<br />'), '', $string);

// It is conceivable that people might still want single line-breaks
// without breaking into a new paragraph.
if ($line_breaks == true)
    return '<p>'.preg_replace(array("/([\n]{2,})/i", "/([^>])\n([^<])/i"), array("</p>\n<p>", '$1<br'.($xml == true ? ' /' : '').'>$2'), trim($string)).'</p>';
else 
    return '<p>'.preg_replace(
    array("/([\n]{2,})/i", "/([\r\n]{3,})/i","/([^>])\n([^<])/i"),
    array("</p>\n<p>", "</p>\n<p>", '$1<br'.($xml == true ? ' /' : '').'>$2'),

    trim($string)).'</p>'; 
}

Answer:

Here is another approach that doesn’t use regular expressions. Note, this function will remove any single line-breaks.

function nl2p($string)
{
    $paragraphs = '';

    foreach (explode("\n", $string) as $line) {
        if (trim($line)) {
            $paragraphs .= '<p>' . $line . '</p>';
        }
    }

    return $paragraphs;
}

If you only need to do this once in your app and don’t want to create a function, it can easily be done inline:

<?php foreach (explode("\n", $string) as $line): ?>
    <?php if (trim($line)): ?>
        <p><?=$line?></p>
    <?php endif ?>
<?php endforeach ?>

Answer:

I also wrote a very simple version:

function nl2p($text)
{
    return '<p>'.str_replace(array("\r\n", "\r", "\n"), '</p><p>', $text).'</p>';
}

Answer:

@Laurent’s answer wasn’t working for me – the else statement was doing what the $line_breaks == true statement should have been doing, and it was making multiple line breaks into <br> tags, which PHP’s native nl2br() already does.

Here’s what I managed to get working with the expected behavior:

function nl2p( $string, $line_breaks = true, $xml = true ) {

    // Remove current tags to avoid double-wrapping.
    $string = str_replace( array( '<p>', '</p>', '<br>', '<br />' ), '', $string );

    // Default: Use <br> for single line breaks, <p> for multiple line breaks.
    if ( $line_breaks == true ) {
        $string = '<p>' . preg_replace(
            array( "/([\n]{2,})/i", "/([\r\n]{3,})/i", "/([^>])\n([^<])/i" ),
            array( "</p>\n<p>", "</p>\n<p>", '$1<br' . ( $xml == true ? ' /' : '' ) . '>$2' ),
            trim( $string ) ) . '</p>';

    // Use <p> for all line breaks if $line_breaks is set to false.
    } else {
        $string = '<p>' . preg_replace(
            array( "/([\n]{1,})/i", "/([\r]{1,})/i" ),
            "</p>\n<p>",
            trim( $string ) ) . '</p>';
    }

    // Remove empty paragraph tags.
    $string = str_replace( '<p></p>', '', $string );

    // Return string.
    return $string;

}

Answer:

Here’s an approach that comes with a reverse method to replace paragraphs back to regular line breaks and vice versa.

These are useful to use when building a form input. When saving a users input you may want to convert line breaks to paragraph tags, however when editing the text in a form, you may not want the user to see any html characters. Then we would replace the paragraphs back to line breaks.

// This function will convert newlines to HTML paragraphs
// without paying attention to HTML tags. Feed it a raw string and it will
// simply return that string sectioned into HTML paragraphs
function nl2p($str) {
    $arr=explode("\n",$str);
    $out='';

    for($i=0;$i<count($arr);$i++) {
        if(strlen(trim($arr[$i]))>0)
            $out.='<p>'.trim($arr[$i]).'</p>';
    }
    return $out;
}

// Return paragraph tags back to line breaks
function p2nl($str)
{
    $str = preg_replace("/<p[^>]*?>/", "", $str);
    $str = str_replace("</p>", "\r\n", $str);
    return $str;
}

Answer:

Expanding upon @NaturalBornCamper’s solution:

function nl2p( $text, $class = '' ) {
    $string = str_replace( array( "\r\n\r\n", "\n\n" ), '</p><p>', $text);
    $string = str_replace( array( "\r\n", "\n" ), '<br />', $string);
    return '<p' . ( $class ? ' class="' . $class . '"' : '' ) . '>' . $string . '</p>';
}

This takes care of both double line breaks by converting them to paragraphs, and single line breaks by converting them to <br />

Answer:

Just type this between your lines:

echo '<br>';

This will give you a new line.