Assignment_module_4.php

<?php

//Q 1: Write a PHP function to sort an array of strings by their length, in ascending order. (Hint: You can use the usort() function to define a custom sorting function.)

function sort_arr_by_length($arr) {
    usort($arr, function($a, $b) {
        return strlen($a) - strlen($b);
    });
    return $arr;
}

$fruits = array("apple", "banana", "pear", "orange", "mango");
$arr = sort_arr_by_length($fruits);
print_r($arr);



//Q 2: Write a PHP function to concatenate two strings, but with the second string starting from the end of the first string.

function concat_strings_with_reverse($str1, $str2): string {
    $str2_rev = strrev($str2);
    return $str1 . $str2_rev;
}

$str1 = "Hello";
$str2 = "World";
$result = concat_strings_with_reverse($str1, $str2);
echo $result;



//Q 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_and_return_new_arr($arr) {
    array_shift($arr);
    array_pop($arr);
    return $arr;
}
$fruits = array("apple", "banana", "pear", "orange", "mango");
$new_arr = remove_first_last_element_and_return_new_arr($fruits);
print_r($new_arr);

//Q 4: Write a PHP function to check if a string contains only letters and whitespace.

function string_contains_only_letters_and_whitespace($str): bool|int {
    return preg_match('/^[a-zA-Z\s]+$/', $str);
}
$str1 = "Hello world";
$result = string_contains_only_letters_and_whitespace($str1);
print_r($result);



//Q 5: Write a PHP function to find the second-largest number in an array of numbers.

function second_largest_element($arr) {
    $largest = $arr[0];
    $second_largest = $arr[0];
    $arr_length = count($arr);
    for ($i = 1; $i < $arr_length; $i++) {
        if ($arr[$i] > $largest) {
            $second_largest = $largest;
            $largest = $arr[$i];
        } elseif ($arr[$i] > $second_largest && $arr[$i] != $largest) {
            $second_largest = $arr[$i];
        }
    }
    return $second_largest;
}

$arr = array(2, 5, 3, 8, 7);
$second_largest = second_largest_element($arr);
echo $second_largest;