php - Problems with array Statement -

hello friends problem statement 2 string

$i=0; $arr['lam'] = preg_replace('/\s+/', 'd', $arr['lam']);  print_r($arr); ///array ( [id] => 123 [lam] => d )  echo '_'.$arr['lam'].'_'; ///_d_ if($arr['lam']!='d'){ $i++; } echo $i; //1 

why $i==1?

this works expected:

<?php  $i=0;  $arr = array('id' => 123, 'lam' => ' '); $arr['lam'] = preg_replace('/\s+/', 'd', $arr['lam']);  print_r($arr); // array ( [id] => 123 [lam] => d )  echo '_'.$arr['lam'].'_'; // _d_  if($arr['lam'] != 'd'){   $i++; }  echo $i; // 0  ?> 

keep in mind regex /\s+/ replace white-space characters. may possible 'd', while 'd', contains other content. don't know goal code, looks should improve regular expression based on input.