Invalid argument supplied for foreach() PHP error

The invalid argument supplied for foreach() the error occurs when PHP’s built-in foreach() tries to iterate over a data structure that is not recognized as an array or
object.

Example

<?php 
    function get_list () {
        // a list/array, a boolean FALSE is returned.
        return false;
    }
    // Get the array
    $lists = get_list();
    foreach($lists as $array_item) {
        //Do something.
    }

Output: warning invalid argument supplied for foreach() in php

The error occurred because the get_list() function returned a boolean value instead of an array. To resolve this error, perform a check before the foreach() function so that the error can be circumvented.

The Resolve

<?php
    function get_list () {
        return false; //list/array, a boolean FALSE is returned.
    }
    $lists = get_list(); //Get the array

    if (is_array($lists) || is_object($lists)) {
        foreach($lists as $array_item) {
            //Do something.        
        }
    } else { 
        echo "Unfortunately, an error."; //If $lists was not an array
    }

Output: Unfortunately, an error.