<?php
 
mb_internal_encoding('utf-8');
 
$text = "Аргентина любит негра";
$result= "Палиндром";
$result2= "Не палиндром";
$text = mb_strtolower($text);
 
$text = str_replace(" ","",$text);
 
$length = mb_strlen($text);
$halfLength = floor($length/2);
for ($i=0; $i==$halfLength; $i++) {
	$o=-$i-1;
	$comparison1=mb_substr($text,$i,1);
    $comparison2=mb_substr($text,$o,1);
    echo "$comparison1 \n";
    echo "$comparison2 \n";
 if ($comparison1==$comparison2) {
    $word1=$word1 . $comparison1;
    $word1=$word1 . $comparison1;
    } else { 
 	echo "Результат: $result2";
 }}
 if($word1==$word2) {
 	echo "Результат: $result \n";
 }