<?php
 
$regexp = '/(\\b([a-zA-Z]+)([а-яёА-ЯЁ]+)\\b)|(\\b([а-яёА-ЯЁ]+)([a-zA-Z]+)([а-яёА-ЯЁ]+)\\b)|(\\b([а-яёА-ЯЁ]+)([a-zA-Z]+)\\b)|(\\b([a-zA-Z]+)([а-яёА-ЯЁ]+)([a-zA-Z]+)\\b)/u';
$text = 'Kartоn это картoнка frоntend-разрaботка';
 
$matches = array();
preg_match_all($regexp, $text, $matches);
 
$regexpCorrect = ['/\\b([a-zA-Z]+)([а-яёА-ЯЁ]+)\\b/u', '/\\b([а-яёА-ЯЁ]+)([a-zA-Z]+)([а-яёА-ЯЁ]+)\\b/u', '/\\b([а-яёА-ЯЁ]+)([a-zA-Z]+)\\b/u', '/\\b([a-zA-Z]+)([а-яёА-ЯЁ]+)([a-zA-Z]+)\\b/u'];
$changed = ['[$1]$2', '$1[$2]$3', '$1[$2]', '$1[$2]$3'];
 
for($i = 0; $i < count($matches[0]); $i++) {
  echo "Опечатка в ".preg_replace($regexpCorrect, $changed, $matches[0][$i])."\n";
};
 

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