Illegal string offset Warning PHP

Illegal string offset Warning PHP. Whenever you see this error. you will feel that its messed up our code. But its a simple mistake we did it on the array of parameter.  Normally we have an array with key and its value as like the following one.

<?php 
$test_array = array(
          'first_key'  => 'first',
          'second_key' => 'second',
          'third_key'  => 'third',
          'four_key'   => 'four'
);
?>

Here the above array has some values. But when you call this array with not set parameter it will throw an illegal offset parameter like the following one.

<?php if($test_array['fifth_key'] != 0 ){
    //some code
   }
?>

for such a kind of issues, we can use this way.

<?php if(isset($test_array['fifth_key'])){
         if($test_array['fifth_key'] != 0 ){
            //some code
         }
   }

Here the ” isset ” function will help use to solve this error.