To check if the value of a given variable is alphanumeric in PHP, you can use the ctype_alnum() function. The ctype_alnum() function returns true if all characters in the string are alphanumeric (letters or digits), and false otherwise. It can be used to validate user input or check if a variable contains only alphanumeric characters. For example, you can use ctype_alnum($var) to check if the value of $var is alphanumeric. It's important to note that the ctype_alnum() function only works with string values. If you need to check alphanumericity for numeric values, you can use a combination of is_string() and is_numeric() functions.

PHP originally stood for "Personal Home Page", but it now stands for "PHP: Hypertext Preprocessor", a recursive backronym. This change reflects the shift in PHP's capabilities from being a simple HTML home page builder to a fully-fledged web scripting language. For more details, visit: https://www.php.net/manual/en/faq.general.php#faq.general.name

This statement is false. In PHP, a number is considered an integer as long as it does not contain a decimal point or an exponential form. The range of the number does not affect its classification as an integer. However, the size of the number may affect its storage and representation in memory. Learn more: https://www.php.net/manual/en/language.types.integer.php

The correct option is 1. The main difference between sort() and rsort() in PHP is the order in which they sort the array. The sort() function arranges the elements of an array in ascending order, while the rsort() function sorts the elements in descending order. Both functions work on indexed arrays, not specifically on associative arrays. Additionally, both sort() and rsort() modify the original array directly, rather than returning a new sorted array. Understanding the difference between these functions is important for selecting the appropriate sorting method based on the desired order of the array elements. Learn more: https://www.php.net/manual/en/function.sort.php, https://www.php.net/manual/en/function.rsort.php

The filter_input_array() function in PHP is used to get multiple input values and optionally filter them. It allows you to specify the type of input and the filter to apply. For more details, refer to: http://php.net/manual/en/function.filter-input-array.php

The for loop in PHP tests the condition before executing the block of code. It first evaluates the condition and if it is true, it executes the code block. If the condition is false, the loop is not executed, and the program continues to the next statement after the loop. This allows you to control the execution of the loop based on the condition. Learn more: https://www.php.net/manual/en/control-structures.for.php

To store multiple values in a single variable for easy manipulation, you would use an array in PHP. An array allows you to store multiple values of different data types in a structured manner. Each value is assigned an index or key, allowing for easy access and manipulation. Arrays provide flexibility and convenience for working with collections of data in PHP. Learn more: https://www.php.net/manual/en/language.types.array.php

The fread() function in PHP is used to read a file. It takes the file pointer and the number of bytes to read as arguments and returns the content of the file as a string. Alternatively, file_get_contents() can also be used to read the entire contents of a file into a string.

The filter_input_array() function in PHP is used to get the input values and optionally filter them. It allows you to specify the type of input and the filter to apply. For more details, refer to: http://php.net/manual/en/function.filter-input-array.php

The correct option is 1. The $GLOBALS superglobal in PHP is indeed an associative array. It contains references to all global variables currently defined in the global scope of the script. The keys of the $GLOBALS array are the variable names, and the values are references to the corresponding variables. This allows you to access and manipulate global variables from anywhere within the script using the $GLOBALS superglobal. However, it is important to note that modifying the values of global variables directly through the $GLOBALS superglobal can lead to potential issues and make code harder to maintain. It is generally recommended to minimize the use of global variables and follow good coding practices. Learn more: https://www.php.net/manual/en/reserved.variables.globals.php