php check if value exists in associative array code example

Example 1: what is use of in_array() function in php

The in_array() function is an inbuilt function in PHP. 
The in_array() function is used to check whether a given value exists in an array or not.
It returns TRUE if the given value is found in the given array, and FALSE otherwise.

  <?php
  
$people = array("Peter", "Joe", "Glenn", "Cleveland");

if (in_array("Glenn", $people))
  {
  echo "Match found";
  }
else
  {
  echo "Match not found";
  }

?>

Example 2: keys of array exist in array

function findKey($array, $keySearch)
{
    foreach ($array as $key => $item) {
        if ($key == $keySearch) {
            echo 'yes, it exists';
            return true;
        } elseif (is_array($item) && findKey($item, $keySearch)) {
            return true;
        }
    }
    return false;
}