Set - 4

Question 1 :

How can we create a database using PHP and mysql? 

Answer :

We can create MySQL database with the use of mysql_create_db($databaseName) to create a database.


Question 2 :

How many ways we can retrieve the date in result set of mysql using php? 

Answer :

As individual objects so single record or as a set or arrays.


Question 3 :

Can we use include ("abc.php") two times in a php page "makeit.php"?

Answer :

Yes


Question 4 :

For printing out strings, there are echo, print and printf. Explain the differences?

Answer :

echo is the most primitive of them, and just outputs the contents following the construct to the screen. print is also a construct (so parentheses are optional when calling it), but it returns TRUE on successful output and FALSE if it was unable to print out the string. However, you can pass multiple parameters to echo, like:

echo 'Welcome ', 'to', ' ', 'techpreparations!';

and it will output the string "Welcome to techpreparations!" print does not take multiple parameters. It is also generally argued that echo is faster, but usually the speed advantage is negligible, and might not be there for future versions of PHP. printf is a function, not a construct, and allows such advantages as formatted output, but it's the slowest way to print out data out of echo, print and printf.


Question 5 :

I am writing an application in PHP that outputs a printable version of driving directions. It contains some long sentences, and I am a neat freak, and would like to make sure that no line exceeds 50 characters. How do I accomplish that with PHP? 

Answer :

On large strings that need to be formatted according to some length specifications, use wordwrap() or chunk_split().


Question 6 :

What's the output of the ucwords function in this example?

$formatted = ucwords("TECHPREPARATIONS IS COLLECTION OF INTERVIEW QUESTIONS");
print $formatted;

What will be printed is TECHPREPARATIONS IS COLLECTION OF INTERVIEW QUESTIONS.

Answer :

ucwords() makes every first letter of every word capital, but it does not lower-case anything else. To avoid this, and get a properly formatted string, it's worth using strtolower() first.


Question 7 :

What's the difference between htmlentities() and htmlspecialchars()?

Answer :

htmlspecialchars only takes care of <, >, single quote ', double quote " and ampersand. htmlentities translates all occurrences of character sequences that have different meaning in HTML.


Question 8 :

How can we extract string "abc.com" from a string "mailto:info@abc.com?subject=Feedback" using regular expression of PHP?

Answer :

$text = "mailto:info@abc.com?subject=Feedback";
preg_match('|.*@([^?]*)|', $text, $output);
echo $output[1];

Note that the second index of $output, $output[1], gives the match, not the first one, $output[0].


Question 9 :

So if md5() generates the most secure hash, why would you ever use the less secure crc32() and sha1()?

Answer :

Crypto usage in PHP is simple, but that doesn't mean it's free. First off, depending on the data that you're encrypting, you might have reasons to store a 32-bit value in the database instead of the 160-bit value to save on space. Second, the more secure the crypto is, the longer is the computation time to deliver the hash value. A high volume site might be significantly slowed down, if frequent md5() generation is required.


Question 10 :

How can we destroy the session, how can we unset the variable of a session?

Answer :

session_unregister() - Unregister a global variable from the current session
session_unset() - Free all session variables


Question 11 :

What are the different functions in sorting an array? 

Answer :

Sorting functions in PHP:

asort()
arsort()
ksort()
krsort()
uksort()
sort()
natsort()
rsort()

 


Question 12 :

How can we know the count/number of elements of an array?

Answer :

2 ways:
a) sizeof($array) - This function is an alias of count()
b) count($urarray) - This function returns the number of elements in an array.
Interestingly if you just pass a simple var instead of an array, count() will return 1.


Question 13 :

How many ways we can pass the variable through the navigation between the pages?

Answer :

At least 3 ways: 
1. Put the variable into session in the first page, and get it back from session in the next page. 
2. Put the variable into cookie in the first page, and get it back from the cookie in the next page. 
3. Put the variable into a hidden form field, and get it back from the form in the next page.


Question 14 :

What is the maximum length of a table name, a database name, or a field name in MySQL?

Answer :

Database name: 64 characters
Table name: 64 characters
Column name: 64 characters


Question 15 :

How many values can the SET function of MySQL take?

Answer :

MySQL SET function can take zero or more values, but at the maximum it can take 64 values.