Answer:- The header() function is used to send a raw HTTP header to a client. It must be called before sending the actual output. For example, you cant print any HTML element before using this function.

Answer:- The isset() function checks if the variable is defined and not null.

Answer:- PHP parameterized functions are functions with parameters. You can pass any number of parameters inside a function. These given parameters act as variables inside your function. They are specified inside the parentheses, after the function name. Output depends upon dynamic values passed as parameters into the function.

Answer:- PHP supports variable length argument function. It means you can pass 0, 1 or n number of arguments in function. To do this, you need to use 3 ellipses (dots) before the argument name. The 3 dot concept is implemented for variable length argument since PHP 5.6.

Answer:- PHP supports variable length argument function. It means you can pass 0, 1 or n number of arguments.

Answer:- An array is used to store multiple values in a single value. In PHP, it orders maps of pairs of keys and values. It saves the collection of the data type.

Answer:- There are three types of array in PHP: Indexed array: an array with a numeric key. Associative array: an array where each key has its specific value. Multidimensional array: an array containing one or more arrays within itself.

Answer:- There are many array functions in PHP: array(), array_change_key_case(), array_chunk(), count(), sort(), array_reverse(), array_search(), array_intersect()

Answer:- The indexed array holds elements in an indexed form which is represented by number starting from 0 and incremented by 1. For example: $season=array("summer","winter","spring","autumn"); The associative array holds elements with name. For example: $salary=array("Sonoo"=>"350000","John"=>"450000","Kartik"=>"200000");

Answer:- The strlen() function is used to get the length of the string.

Answer:- here are many array functions in PHP: strtolower(), strtoupper(), ucfirst(), lcfirst(), ucwords(), strrev(), strlen()

Answer:- There are two methods GET and POST.

Answer:- You can use JavaScript submit() function to submit the form without explicitly clicking any submit button.

Answer:- PHP allows you to include file so that page content can be reused again. There are two ways to add the file in PHP. include require