Interview Questions PHP

PHP


11. How can we create a database using php?
mysql_create_db($database_name);

12. Explain include(), include_once, require() and require_once.
include() The include() function takes all the content in a specified file and includes it in the current file. If an error occurs, the include() function generates a warning, but the script will continue execution. 
include_once() File will not be included more than once. If we want to include a file once only and further calling of the file will be ignored then we have to use the PHP function include_once().
require() The require() function is identical to include(), except that it handles errors differently. The require() generates a fatal error, and the script will stop.
require_once() The required file is called only once when a page is open and further calling of the file will be ignored.

13. What are the different types of errors in php?
Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although, as you will see, you can change this default behavior. 
Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place.

14. What are the Formatting and Printing Strings available in PHP?
printf() Displays a formatted string 
sprintf() Saves a formatted string in a variable
fprintf() Prints a formatted string to a file
number_format() Formats numbers as strings

15. How to find a length of a string?
strlen()

16. What is the functionality of the function strstr and stristr?
strstr() returns part of a given string from the first occurrence of a given substring to the end of the string. 
For example: strstr("username@example.com","@") will return "@example.com".
stristr() is idential to strstr() except that it is case insensitive.

17. How can we get second of the current time using date function?
<?php $second = date("s"); ?>

18. What is the difference between the functions unlink and unset?
unlink() deletes the given file from the file system. 
unset() makes a variable undefined.

19. What is the difference between ereg_replace() and eregi_replace()?
eregi_replace() function is identical to ereg_replace() except that it ignores case distinction when matching alphabetic characters.

20. What is the difference between characters 23 and x23?
The first one is octal 23, the second is hex 23.