PHP code to generate safe URL?

Ah, slugification

// This function expects the input to be UTF-8 encoded. function slugify($text) { // Swap out Non "Letters" with a - $text = preg_replace('/[^\\pL\d]+/u', '-', $text); // Trim out extra -'s $text = trim($text, '-'); // Convert letters that we have left to the closest ASCII representation $text = iconv('utf-8', 'us-ascii//TRANSLIT', $text); // Make text lowercase $text = strtolower($text); // Strip out anything we haven't been able to convert $text = preg_replace('/[^-\w]+/', '', $text); return $text; } 

This works fairly well, as it first uses the unicode properties of each character to determine if it's a letter (or \d against a number) - then it converts those that aren't to -'s - then it transliterates to ascii, does another replacement for anything else, and then cleans up after itself. (Fabrik's test returns "arvizturo-tukorfurogep")

I also tend to add in a list of stop words - so that those are removed from the slug. "the" "of" "or" "a", etc (but don't do it on length, or you strip out stuff like "php")

If “invalid” means non-alphanumeric, you can do this:

function foo($str) { return trim(preg_replace('/[^a-z0-9]+/', '-', strtolower($str)), '-'); } 

This will turn $str into lowercase, replace any sequence of one or more non-alphanumeric characters by one hyphen, and then remove leading and trailing hyphens.

var_dump(foo("The Great Book of PHP") === 'the-great-book-of-php'); var_dump(foo("The Greatest !@#$ Book of PHP") === 'the-greatest-book-of-php'); var_dump(foo("Funny title ") === 'funny-title'); 

You can use a simple regular expression for this purpose:

<?php function safeurl( $v ) { $v = strtolower( $v ); $v = preg_replace( "/[^a-z0-9]+/", "-", $v ); $v = trim( $v, "-" ); return $v; } echo "<br>www.mysite.com/book/12345/" . safeurl( "The Great Book of PHP" ); echo "<br>www.mysite.com/book/12345/" . safeurl( "The Greatest !@#$ Book of PHP" ); echo "<br>www.mysite.com/book/12345/" . safeurl( " Funny title " ); echo "<br>www.mysite.com/book/12345/" . safeurl( "!!Even Funnier title!!" ); ?> 

If you want to allow only letters, digits and underscore (usual word characters) you can do:

$str = strtolower(preg_replace(array('/\W/','/-+/','/^-|-$/'),array('-','-',''),$str)); 

It first replaces any non-word character(\W) with a -.
Next it replaces any consecutive - with a single -
Next it deletes any leading or trailing -.

Working link

This code comes from CodeIgniter's url helper. It should do the trick.

function url_title($str, $separator = 'dash', $lowercase = FALSE) { if ($separator == 'dash') { $search = '_'; $replace = '-'; } else { $search = '-'; $replace = '_'; } $trans = array( '&\#\d+?;' => '', '&\S+?;' => '', '\s+' => $replace, '[^a-z0-9\-\._]' => '', $replace.'+' => $replace, $replace.'$' => $replace, '^'.$replace => $replace, '\.+$' => '' ); $str = strip_tags($str); foreach ($trans as $key => $val) { $str = preg_replace("#".$key."#i", $val, $str); } if ($lowercase === TRUE) { $str = strtolower($str); } return trim(stripslashes($str)); } 

Replace special chars for white spaces and then replace white spaces for "-". str_replace?

Use a regex replace to remove all non word characters. For example:

str_replace('[^a-zA-Z]+', '-', $input)

<?php $input = " The Great Book's of PHP "; $output = trim(preg_replace(array("`'`", "`[^a-z]+`"), array("", "-"), strtolower($input)), "-"); echo $output; // the-great-books-of-php 

This trims trailing dashes and doesn't do things like "it's raining" -> "it-s-raining" as most solutions tend to do.