An Interview , in PHP . best he answered
Raj is having well hands-on experince in php , He is getting into php technical interview round
Interviewer started by asking .
" What are different areas , where PHP can be used ?"Raj replied :
There are three main areas where PHP scripts are used.
1. Server-side scripting : Php run on the web server, with a connected PHP installation. You can access the PHP program output with a web browser .
2. Command Line Scripting : PHP Script will also run without any server or browser with help of PHP parser .
3 . Writing desktop applications : PHP can also be used to create a desktop application with a graphical user interface .We can use PHP-GTK to write such programs.
Interviewer :
"Explain file handling in php and all their diffrent operation like(reading , writing updating etc..)in detail"
Raj replies :
PHP has several functions for Creating, Reading, Open and Closing and Editing Files.PHP readfile() Function , The readfile() function reads a file and writes it to the output buffer. Example is given below
PHP Open File - fopen() . A better method to open files is with the fopen() function. This function gives you more options than the readfile() function.Example is given below.
PHP Read File - fread(). The fread() function reads from an open file. The first parameter of fread() contains the name of the file to read from and the second parameter specifies the maximum number of bytes to read. Example is given below
PHP Close File - fclose(). The fclose() function is used to close an open file. Example is given below.
PHP Read Single Line - fgets() . The fgets() function is used to read a single line from a file. Example is given below
PHP Check End-Of-File - feof(). The feof() function checks if the "end-of-file" (EOF) has been reached.Example is given below
PHP Read Single Character - fgetc() .The fgetc() function is used to read a single character from a file. Example is given below.
PHP Write to File - fwrite() .The fwrite() function is used to write to a file.Example is given below
Interviewer next question :
"Whats the difference between mysql_connect and mysql_pconnect ?"
Raj Replied :
mysql_connect - Open a connection to a MySQL Server. Connection will be closed as soon as the execution of the script ends, unless it's closed earlier by explicitly calling mysql_close().Example is given below.
While mysql_pconnect Establishes a persistent connection to a MySQL server. When a persistent connection is requested, PHP checks if there's already an identical persistent connection (that remained open from earlier) - and if it exists, it uses it.
Example is given below.
Interviwer next question :
Explain PHP MySql functions : mysql_fetch_array , mysql_fetch_assoc , mysql_fetch_row , mysql_fetch_object and their differences.
Raj replied :
mysql_fetch_array Fetch a result row as an associative array, a numeric array, or both
mysql_fetch_array ( resource $result [, int $result_type = MYSQL_BOTH ] )
result_type is a constant and can take the following values:
MYSQL_ASSOC, MYSQL_NUM, and MYSQL_BOTH.
Example is given below.
mysql_fetch_assoc Fetch a result row as an associative array
mysql_fetch_assoc ( resource $result )
Example is given below
mysql_fetch_row Fetches one row of data from the result associated with the specified result identifier. The row is returned as an array.
mysql_fetch_row ( resource $result )
Example is given below
mysql_fetch_object Fetch a result row as an object
mysql_fetch_object( resource $result )
Example is given below
Interviewer next question :
What is difference between COOKIES and SESSION. Explain both.
Raj replied :
A COOKIE is a small piece of text stored on a user's computer by their browser. Each time the users' web browser interacts with a web server it will pass the cookie information to the web server.
This means that cookies that relate to www.example.com will not be sent to www.exampledomain.com.
Common uses for COOKIES are authentication, storing of site preferences, shopping cart items,and server session identification.
A SESSION can be defined as a server-side storage of information that is desired to persist throughout the user's interaction with the web site or web application.
Instead of storing large and constantly changing information via COOKIES in the user's browser, only a unique identifier is stored on the client side (called a "session id(SSID)").
This session id is passed to the web server every time the browser makes an HTTP request (ie a page link or AJAX request).
The web application pairs this session id with it's internal database and retrieves stored variables for use by the requested page.
Interviewer next question :
What is Sql injection and how it can be prevented?
Raj replied:
SQL Injection is the placement of malicious code in SQL statements, via web page input.
SQL Injection is one of the most common web hacking techniques.
For Example The original purpose of the below code was to create an SQL statement to select a user, with a given user id.
If there is nothing to prevent a user from entering "wrong" input, the user can enter some "smart" input like this: , UserId: 105 OR 1=1
Then, the SQL statement will look like this: , SELECT * FROM Users WHERE UserId = 105 OR 1=1;
The SQL above is valid and will return ALL rows from the "Users" table, since OR 1=1 is always TRUE.
A hacker might get access to all the user detail, that will be very dangerous.
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SQL Injection can prevented by using
(1). mysqli_real_escape_string
The mysqli_real_escape_string() function escapes special characters in a string for use in an SQL statement.
Another way preventing SQL Injection is by using
using prepared statment
Example is given below
Interviewer next question :
What is CrossSite Scripting ?
Raj replied:
Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into trusted web sites.
Example is given below
The end user’s browser has no way to know that the script should not be trusted, and will execute the script , because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and passes to attcker .
These scripts can even rewrite the content of the HTML page.
Example is given below
Interviewer Next Question :
Explain Rest Services .
Raj replied :
REST defines a set of architectural principles by which you can design Web services that focus on a system's resources, including how resource states are addressed and transferred over HTTP by a wide range of clients written in different languages.
REST Web service follows four basic design principles:
* Use HTTP methods explicitly.
* Be stateless.
* Expose directory structure-like URIs.
* Transfer XML, JavaScript Object Notation (JSON),
or both.
Interviewer next question :
Explain SOAP.
Raj replied :
SOAP stands for Simple Object Access Protocol.
SOAP provides the envelope for sending Web Services messages over the Internet/Internet. It is part of the set of standards specified by the W3C
The SOAP envelope contains two parts:
* An optional header providing information on authentication, encoding of data, or how a recipient of a SOAP message should process the message.
* The body that contains the message. These messages can be defined using the WSDL specification.
Interviewer next question
What is difference between include and require ?
Raj replied:
With the include or require statement. We used to insert the content of one PHP/html file into another PHP file (before the server executes it)
In include - (if source file missing it'll give warning and continue execution), while in require - (if source file missing it'll give error and halt execution),)
With the include or require statement. We used to insert the content of one PHP/html file into another PHP file (before the server executes it)
In include - (if source file missing it'll give warning and continue execution), while in require - (if source file missing it'll give error and halt execution),)
Interviewer Next Question :
Explain session_set_save_handler ?
Raj replied :
To maintain the session data, we can use session_set_save_handler function.
This function provide 6 callback functions which call automatically.
openFunction will be called automatically when session start.
closeFunction will be called automatically when session end.
readFunction will be called automatically when you read the session.
writeFunction will be called automatically when you write in the session.
destroyFunction will be called automatically when you destroy in the session.
gcFunction will be called automatically when session inactive for long time.
Interviewer Next Question :
How to convert string to array and array to string in php?
Raj replied:
Explode convert string to array , example given below
Implode convert array to string , example given below
Interviewer Next Question :
How to scrape the data from website using CURL?
Raj replied :
To scrap the data from website, Website must be public and open for scrapable. In the blow code, Just update the CURLOPT_URL to which websites data you want to scrap.
Interviewer Next Question :
How to explode a string using multiple delimiters("," and "|" )?
Raj replied:
To explode a string with multiple delimeters , we use preg_split
$string='php, interview | questions , and | answers ';
$output = preg_split( "/(\,|\|)/", $string );
print_r($output );
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Raj replied to all question very well
