php - How can I detect and print what characters str_replace() changed? -

i'm using code replace words each other.

in scenario, in same time...just there 1 same word in #old , $string example $string = "da" , $string = "fjb" true $string = "ba" or $string = "dahjc" false.

$string = "sdfsdfsdfa" $old = array("a", "b", "c"); $new   = array("1", "2", "3"); $string = str_replace($old, $new, $string); 

how can detect characters got replaced str_replace() , print this:

result: 'a' replaced '1' 

<?php $oldstring = "sdfsdfsdfa"; $main_array=array("a"=>"1","b"=>"2", "c"=>"3"); $old=array_keys($main_array); $new=array_values($main_array);  $newstring = str_replace($old, $new, $oldstring); foreach ($main_array $key => $value) {     if (strpos($oldstring,$key) !== false) {     echo "result: {$key} replaced {$value} <br>";     } } echo '<b>'.$oldstring.'</b><br>'; echo $newstring; ?>