PHP Exercises: Get the index of the last element for which the given function returns a truth value

PHP: Exercise-82 with Solution

Write a PHP program to get the index of the last element for which the given function returns a truth value.

Sample Solution:

PHP Code:

<?php
// Function definition for 'find_last_Index' that takes an array of items and a filtering function as parameters
function find_last_Index($items, $func)
{
    // Use 'array_filter' to filter the items based on the given function and retrieve the keys of the filtered items
    $keys = array_keys(array_filter($items, $func));

    // Use 'array_pop' to retrieve and return the last key from the array of filtered keys
    return array_pop($keys);
}

// Call 'find_last_Index' with an array and an anonymous function checking for odd numbers, then display the result using 'echo'
echo find_last_Index([1, 2, 3, 4], function ($n) {
    return ($n % 2) === 1;
});

// Display a newline
echo "\n";

// Call 'find_last_Index' with an array and an anonymous function checking for even numbers, then display the result using 'echo'
echo find_last_Index([1, 2, 3, 4], function ($n) {
    return ($n % 2) === 0;
});

?>

Explanation:

• Define find_last_Index Function:
• The function find_last_Index accepts:
• $items: an array of items to search through.
• $func: a filtering function used to determine which items to include.
• Filter Array and Retrieve Keys:
• array_filter($items, $func): Filters $items based on the condition defined in $func.
• array_keys(...): Retrieves the keys (indices) of the filtered items.
• Return the Last Key:
• array_pop($keys): Removes and returns the last key from the filtered keys array, which corresponds to the last item in $items that met the condition.
• Function Calls and Output:
• find_last_Index([1, 2, 3, 4], function ($n) { return ($n % 2) === 1; }):
• Filters for odd numbers, returns 2, the index of the last odd number (3).
• find_last_Index([1, 2, 3, 4], function ($n) { return ($n % 2) === 0; }):
• Filters for even numbers, returns 3, the index of the last even number (4).
• Purpose:
• The function find_last_Index provides a way to find and return the index of the last element in an array that meets a specified condition, enabling flexible data retrieval based on custom criteria.

Output:

2
3

Flowchart:

PHP Code Editor:

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