PHP Questions

Question 1

What does (=) do?

Answer 1

Assigns a value

Question 2

What does (==) do?

Answer 2

Checks if values are the same

Question 3

What does (===) do?

Answer 3

Checks if values are the same and of same type

Question 4

What does echo do?

Answer 4

Outputs what is passed to it

Question 5

What does print do?

Answer 5

Outputs what is passed to it and acts as function for passing comples statements

Question 6

What does printf do?

Answer 6

Used for formatting output

Question 7

What does include do?

Answer 7

Includes a file each time it’s called

Question 8

What does include_once do?

Answer 8

Will only include file when first called

Question 9

What does require do?

Answer 9

Same as include but results in error if file not found

Question 10

How are variables passed to functions?

Answer 10

By value unless it is passed with an ‘&’, which would make it by reference

Question 11

What is the differance between crypt() and md5()?

Answer 11

crypt() is used for encrypting something that be decrypted later. md5() produces a hash, which cannot be decrypted

Question 12

What are PHP Statics?

Answer 12

Elements that can be accessed from any context. Like calling a method from another class without needing to instantiate that class

Question 13

What is POST?

Answer 13

An array of variable passed via http post method

Question 14

What is GET?

Answer 14

Array of variable passed via http url parameters

Question 15

What is SESSION?

Answer 15

Array of variables that can be preserved accross acccess of a site, usually stored in memory or database

Question 17

What is inheritance?

Answer 17

Mechanism of deriving a new class from an existing class while keeping attributes and behaviors of parent class

Question 18

What is polymorphism?

Answer 18

Classes with differant functionality while sharing a common interface

Question 19

What is an abstract class?

Answer 19

A mix between an interface and a class. It defines a class that must be extended in order to be used.

Question 20

What is encapsulation?

Answer 20

Wrapping of data within an object with data structures and methods to act on them

Question 21

Whats differant in PHP 5 over PHP 4

Answer 21

Static methods and properties, visibility propherties (public, private, protected), constructors and destructors, abstract classes, interfaces, magic metods, autoload, type hinting, exceptions

Question 22

What does public property do?

Answer 22

Allows a method or property to be accessible and modifiable by everyone

Question 23

What does private property do?

Answer 23

Makes methods and properties available to the class they reside in only

Question 24

What does protected property do?

Answer 24

Makes methods and properties available to class they reside in, and child or parent classes

Question 25

What are interfaces?

Answer 25

An interface defines the methods a class must implement without having to define how they are handled

Question 26

What are magic methods?

Answer 26

PHP functions with reserved names startng with '\_\_' : \_\_call()

Question 27

What does type hinting do?

Answer 27

Allows for enforcement of variable types passed to functions or methods

Question 28

What is registered globals?

Answer 28

PHP setting that allows for creation of global variables for many server variable and query string parameters - should be off