PHP Interview Questions with Answers Part 4

on 9:02 AM

This is the new fourth episode of PHP Interview preparation Questions with answers. Check out this collection of PHP Interview Questions with simplified Answers.
  • How To Protect Special Characters in Query String?
  • Are objects passed by value or by reference?
  • What are the differences between DROP a table and TRUNCATE a table?
  • What are the differences between GET and POST methods in form submitting, give the case where we can use GET and we can use POST methods?
  • How do you call a constructor for a parent class?
  • WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?
  • What’s the special meaning of __sleep and __wakeup?
  • How can we submit a form without a submit button?
  • Why doesn’t the following code print the newline properly?
  • Would you initialize your strings with single quotes or double quotes?
How To Protect Special Characters in Query String?
If you want to include special characters like spaces in the query string, you need to protect them by applying the urlencode() translation function. The script below shows how to use urlencode():

print("");
print("
Please click the links below"
." to submit comments about FYICenter.com:
");
$comment = 'I want to say: "It\'s a good site! :->"';
$comment = urlencode($comment);
print(""
.""
."It's an excellent site!

");
$comment = 'This visitor said: "It\'s an average site! :-("';
$comment = urlencode($comment);
print(""
.''
."It's an average site.

");
print("");
?>
Are objects passed by value or by reference?
Everything is passed by value.
What are the differences between DROP a table and TRUNCATE a table?
DROP TABLE table_name - This will delete the table and its data.

TRUNCATE TABLE table_name - This will delete the data of the table, but not the table definition.
What are the differences between GET and POST methods in form submitting, give the case where we can use GET and we can use POST methods?
Anwser 1:

When we submit a form, which has the GET method it displays pair of name/value used in the form at the address bar of the browser preceded by url. Post method doesn't display these values.

Anwser 2:

When you want to send short or small data, not containing ASCII characters, then you can use GET” Method. But for long data sending, say more then 100 character you can use POST method.

Once most important difference is when you are sending the form with GET method. You can see the output which you are sending in the address bar. Whereas if you send the form with POST” method then user can not see that information.

Anwser 3:

What are "GET" and "POST"?

GET and POST are methods used to send data to the server: With the GET method, the browser appends the data onto the URL. With the Post method, the data is sent as "standard input."

Major Difference

In simple words, in POST method data is sent by standard input (nothing shown in URL when posting while in GET method data is sent through query string.

Ex: Assume we are logging in with username and password.

GET: we are submitting a form to login.php, when we do submit or similar action, values are sent through visible query string (notice ./login.php?username=...&password=... as URL when executing the script login.php) and is retrieved by login.php by $_GET['username'] and $_GET['password'].

POST: we are submitting a form to login.php, when we do submit or similar action, values are sent through invisible standard input (notice ./login.php) and is retrieved by login.php by $_POST['username'] and $_POST['password'].

POST is assumed more secure and we can send lot more data than that of GET method is limited (they say Internet Explorer can take care of maximum 2083 character as a query string).

Anwser 4:

In the get method the data made available to the action page ( where data is received ) by the URL so data can be seen in the address bar. Not advisable if you are sending login info like password etc. In the post method the data will be available as data blocks and not as query string in case of get method.

Anwser 5:

When we submit a form, which has the GET method it pass value in the form of query string (set of name/value pair) and display along with URL. With GET we can a small data submit from the form (a set of 255 character) whereas Post method doesn't display value with URL. It passes value in the form of Object and we can submit large data from the form.

Anwser 6:

On the server side, the main difference between GET and POST is where the submitted is stored. The $_GET array stores data submitted by the GET method. The $_POST array stores data submitted by the POST method.
On the browser side, the difference is that data submitted by the GET method will be displayed in the browser’s address field. Data submitted by the POST method will not be displayed anywhere on the browser.
GET method is mostly used for submitting a small amount and less sensitive data. POST method is mostly used for submitting a large amount or sensitive data.
How do you call a constructor for a parent class?
parent::constructor($value)
WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?
Here are three basic types of runtime errors in PHP:

1. 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 you can change this default behavior.

2. 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.

3. 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.

Internally, these variations are represented by twelve different error types
What’s the special meaning of __sleep and __wakeup?
__sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.
How can we submit a form without a submit button?
If you don't want to use the Submit button to submit a form, you can use normal hyper links to submit a form. But you need to use some JavaScript code in the URL of the link. For example:

Submit Me
Why doesn’t the following code print the newline properly?
Because inside the single quotes the \n character is not interpreted as newline, just as a sequence of two characters - \ and n.
Would you initialize your strings with single quotes or double quotes?
Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.

For Previous Parts click below links

PHP Interview Questions with Answers Part 3







http://interviewstar.blogspot.com/2010/08/php-interview-questions-with-answers.html

2 comments:

web dagger said...

Hey thanks a lot for sharing useful interview questions..... which will be very helpful while attending the interviews.....
glad i found ur site...really a very helpful site.....
by the way check out my collection of php interview questions from here: php interview questions

vitomannone333 said...

Hi

I read this post 2 times. It is very useful.

Pls try to keep posting.

Let me show other source that may be good for community.

Source: Program manager interview questions

Best regards
Jonathan.

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