(PHP 4, PHP 5, PHP 7, PHP 8)
rawurlencode — URL-encode according to RFC 3986
stringThe URL to be encoded.
   Returns a string in which all non-alphanumeric characters except
   -_.~ have been replaced with a percent
   (%) sign followed by two hex digits.  This is the
   encoding described in » RFC 3986 for
   protecting literal characters from being interpreted as special URL
   delimiters, and for protecting URLs from being mangled by transmission
   media with character conversions (like some email systems).
  
Example #1 including a password in an FTP URL
<?php
echo '<a href="ftp://user:', rawurlencode('foo @+%/'),
     '@ftp.example.com/x.txt">';
?>
The above example will output:
<a href="ftp://user:foo%20%40%2B%25%2F@ftp.example.com/x.txt">
Or, if you pass information in a PATH_INFO component of the URL:
Example #2 rawurlencode() example 2
<?php
echo '<a href="http://example.com/department_list_script/',
    rawurlencode('sales and marketing/Miami'), '">';
?>
The above example will output:
<a href="http://example.com/department_list_script/sales%20and%20marketing%2FMiami">