warnings - Undefined offset error while printing values from db in php -

undefined offset error occurs while printing values of mysqli_fetch_array() using for loop:

code:

$con=mysqli_connect($serverid,$useid,$passwordid,$dbid);<br> $fieldcheck= "select * userregistrationform";<br> $execfield=mysqli_query($con,$fieldcheck);<br> if(mysqli_num_rows($execfield)>0) {     $idcheck= "select changeid userregistrationform";     $execq0=mysqli_query($con,$idcheck);     $idcmp=mysqli_fetch_array($execq0);     $idlength=count($idcmp);     echo $idlength;     for($x=0;$x < $idlength;$x++) {         echo $idcmp[$x];     } 

note:

1. changeid column in database.

2. the code worksfine when use

   while($idcmp=mysqli_fetch_array($execq0)) {     echo $idcmp['changeid']; } 

but helpful why error occurs if use loop.

when print $idcmp see like:

array('changeid' => 100) 

see, key in array changeid.

when

for($x=0;$x < $idlength;$x++) {     echo $idcmp[$x]; } 

you try access key value 0. there's no key 0 in $idcmp. that's why offset error.