PHP can be embedded directly into HTML. The server interprets the PHP code and outputs the result as HTML to the client's browser. Learn more: https://www.php.net/manual/en/language.basic-syntax.phpmode.php

The true statements about Regular Expressions in PHP are that they are powerful tools for pattern matching and manipulating strings. Regular Expressions provide a concise and flexible way to search, extract, and manipulate text data based on specific patterns. They can be used for tasks like data validation, string substitution, data extraction, and more. Regular Expressions are not used for mathematical calculations, are case-sensitive by default (unless specified otherwise with modifiers), and can handle dynamic inputs by using special characters and metacharacters to define flexible patterns. Learn more: https://www.php.net/manual/en/book.regex.php

Some common use cases for mail functions in PHP include sending email notifications to users, implementing contact forms on websites, and managing newsletter subscriptions. Mail functions provide a way to programmatically send emails from your PHP applications. With mail functions, you can compose email messages, set recipients, add attachments, and handle email delivery. These functions enable you to incorporate email functionality into your PHP applications, enhancing communication and interaction with users.

You can pass a variable by reference in PHP by using the & symbol before the variable name in both the function declaration and the function call. This allows changes made to the parameter inside the function to reflect in the original variable outside the function. For example, you can define a function modifyValue(&$var) that takes a variable by reference and modifies its value. To pass a variable by reference, you can call the function as modifyValue(&$myVar). It's important to note that passing variables by reference should be used with caution, as it can lead to unexpected side effects and make the code harder to maintain. It's recommended to use references sparingly and only when necessary.

The syntax to declare an array in PHP is array(, , ...). Alternatively, you can also use the shorthand syntax [, , ...]. The values can be of any data type, and they are separated by commas. The array can be assigned to a variable or used directly in the code. Learn more: https://www.php.net/manual/en/language.types.array.php#language.types.array.syntax

The key difference between echo and print in PHP is that echo has a void return type, meaning it does not return a value, while print returns a value of 1. Additionally, echo is slightly faster and more efficient than print. Both echo and print can be used to output strings, but print also supports multiple arguments separated by commas. Learn more: https://www.php.net/manual/en/function.echo.php https://www.php.net/manual/en/function.print.php

While PHP can be used for a variety of tasks, one of its most common uses is web scraping, where PHP scripts can be written to automatically gather data from web pages. Learn more: https://www.php.net/manual/en/book.dom.php

In PHP, $_COOKIE is an array that holds cookies sent by the client to the server. It provides access to cookie values. Learn more: http://php.net/manual/en/reserved.variables.cookies.php

The $_FILES superglobal array in PHP holds the information about uploaded files. It provides access to the file name, temporary file location, file size, and other details of the uploaded file. This array is available after a file has been uploaded using an HTML form with the appropriate settings.

A common use case for the $_GET superglobal in PHP is to access data from the URL's query string. This can include parameters or values passed through the URL, such as search queries, page identifiers, or filter criteria. By retrieving data from the query string using $_GET, you can dynamically generate content, perform searches, or filter data based on user input. However, it is not used for retrieving form data using the GET method or processing user input using the POST method. Learn more: https://www.php.net/manual/en/reserved.variables.get.php