How to convert all characters to their html entity equivalent using PHP - php

Question

I want to convert this hello#domain.com to
hello#domain.com
I have tried:
url_encode($string)
this provides the same string I entered, returned with the # symbol converted to %40
also tried:
htmlentities($string)
this provides the same string right back.
I am using a UTF8 charset. not sure if this makes a difference....

Answer 1

Here it goes (assumes UTF-8, but it's trivial to change):
function encode($str) {
$str = mb_convert_encoding($str , 'UTF-32', 'UTF-8'); //big endian
$split = str_split($str, 4);
$res = "";
foreach ($split as $c) {
$cur = 0;
for ($i = 0; $i < 4; $i++) {
$cur |= ord($c[$i]) << (8*(3 - $i));
}
$res .= "&#" . $cur . ";";
}
return $res;
}
EDIT Recommended alternative using unpack:
function encode2($str) {
$str = mb_convert_encoding($str , 'UTF-32', 'UTF-8');
$t = unpack("N*", $str);
$t = array_map(function($n) { return "&#$n;"; }, $t);
return implode("", $t);
}

Answer 2

Much easier way to do this:
function convertToNumericEntities($string) {
$convmap = array(0x80, 0x10ffff, 0, 0xffffff);
return mb_encode_numericentity($string, $convmap, "UTF-8");
}
You can change the encoding if you are using anything different.
Fixed map range. Thanks to Artefacto.

Answer 3

function uniord($char) {
$k=mb_convert_encoding($char , 'UTF-32', 'UTF-8');
$k1=ord(substr($k,0,1));
$k2=ord(substr($k,1,1));
$value=(string)($k2*256+$k1);
return $value;
}
the above function works for 1 character but if you have a string you can do like this
$string="anytext";
$arr=preg_split(//u,$string,-1,PREG_SPLIT_NO_EMPTY);
$temp=" ";
foreach($arr as $v){
$temp="&#".uniord($v);//prints the equivalent html entity of string
}