assignment-4.php

<?php
// 1.Write a PHP function to sort an array of strings by their length, in ascending order.
function sort_strings_by_length($arrayItem) {
    usort($arrayItem, function($a, $b) {
        return strlen($a) - strlen($b);
    });
    return $arrayItem;
}
$strings = array("apple", "banana", "cherry", "date", "elderberry");
$sorted_strings = sort_strings_by_length($strings);
echo '<pre>';
print_r($sorted_strings);
echo '</pre>';
echo "\n"; 

// 2.Write a PHP function to concatenate two strings, but with the second string starting from the end of the first string.
function concatenate_strings_reverse($string1, $string2) {
    $len1 = strlen($string1);
    $len2 = strlen($string2);
    $new_string = substr($string1, 0, $len1-$len2) . strrev($string2);
    return $new_string;
}
$string1 = "Hello World!";
$string2 = "Hello Earth";
$concatenated_string = concatenate_strings_reverse($string1, $string2);
echo "<pre>";
echo $concatenated_string;
echo "</pre>";
echo "\n"; 

// 3.Write a PHP function to remove the first and last element from an array and return the remaining elements as a new array.
function remove_first_last_element($array) {
    array_shift($array);
    array_pop($array);
    return $array;
}
$original_array = array(1, 2, 3, 4, 5);
$new_array = remove_first_last_element($original_array);
echo '<pre>';
print_r($new_array);
echo '</pre>';
echo "\n"; 

// 4.Write a PHP function to check if a string contains only letters and whitespace.
function isLettersAndWhitespaceOnly($str) {
    for ($i = 0; $i < strlen($str); $i++) {
        $char = $str[$i];
        if (!ctype_alpha($char) && !ctype_space($char)) {
            return false;
        }
    }
    return true;
}
$string = "This is a string with only letters and whitespace";
if (isLettersAndWhitespaceOnly($string)) {
    echo "letters and whitespace";
    echo "<\br>";
    echo "\n";
} else {
    echo " non-letter or non-whitespace";
    echo "<br>";
    echo "\n";
}

//5.Write a PHP function to find the second largest number in an array of numbers.
function find_second_largest_number($array) {
    rsort($array);
    return $array[1];
}
$numbers = array(4, 7, 2, 9, 5, 1, 8);
$second_largest_number = find_second_largest_number($numbers);
echo $second_largest_number;
echo "<\br>";
echo "\n";