PHP Interview Questions with Answers Part 5 Posted by Unknown on 5:14 AM

This is the new fifith episode of PHP Interview preparation Questions with answers. Check out this collection of PHP Interview Questions with simplified Answers.

• How can we extract string 'abc.com ' from a string http://info@abc.com using regular expression of php?
• What is the difference between the functions unlink and unset?
• How come the code works, but doesn’t for two-dimensional array of mine?
• How can we register the variables into a session?
• What is the difference between characters \023 and \x23?
• With a heredoc syntax, do I get variable substitution inside the heredoc contents?
• How can we submit form without a submit button?
• How can we create a database using PHP and mysql?
• How many ways we can retrieve the date in result set of mysql using php?
• Can we use include ("abc.php") two times in a php page "makeit.php"?

PHP Interview Questions with Answers Part 4 Posted by Unknown 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?

PHP Interview Questions with Answers Part 3 Posted by Unknown on 12:48 AM

This is the third episode of PHP Interview Questions with answers. Check out this collection of PHP Interview Questions with simplified Answers..

• How do you pass a variable by value?
• WHAT IS THE FUNCTIONALITY OF THE FUNCTIONS STRSTR() AND STRISTR()?
• When are you supposed to use endif to end the conditional statement?
• How can we send mail using JavaScript?
• What is the functionality of the function strstr and stristr?
• What is the difference between ereg_replace() and eregi_replace()?
• How do I find out the number of parameters passed into function9. ?
• What is the purpose of the following files having extensions: frm, myd, and myi? What these files contain?
• If the variable $a is equal to 5 and variable $b is equal to character a, what’s the value of $b?
• Write a query for the following question

PHP Interview Questions with Answers Part 2 Posted by Unknown on 9:16 AM

This is the second episode of PHP Interview Questions with answers. Check out this collection of PHP Interview Questions with simplified Answers..

• What are the differences between require and include, include_once?
• What is meant by urlencode and urldecode?
• How To Get the Uploaded File Information in the Receiving Script?
• What is the difference between mysql_fetch_object and mysql_fetch_array?
• How can I execute a PHP script using command line?
• I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what’s the problem?
• Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example?
• What are the different tables present in MySQL? Which type of table is generated when we are creating a table in the following syntax: create table employee(eno int(2),ename varchar(10))?
• How To Create a Table?
• How can we encrypt the username and password using PHP?

PHP Interview Questions with Answers Part 1 Posted by Unknown on 9:18 AM

Are you a PHP learner or developer? Or you need to update your software development knowledge or need to prepare for a job interview? Check out this collection of PHP Interview Questions with simplified Answers..

• What's PHP
• What Is a Session?
• What is meant by PEAR in php?
• How can we know the number of days between two given dates using PHP?
• How can we repair a MySQL table?
• What is the difference between $message and $message?
• What Is a Persistent Cookie?
• What does a special set of tags do in PHP?
• How do you define a constant?
• How To Write the FORM Tag Correctly for Uploading Files?

For Answers Click Read More

PHP Q/A Posted by Unknown on 4:06 AM

Introduction
What does a special set of tags do in PHP?
- The output is displayed directly to the browser.
Full Content

1. What’s the difference between include and require? - It’s how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.
2. I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what’s the problem? - PHP Interpreter treats numbers beginning with 0 as octal.
   
3. Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example? - In this example it wouldn’t matter, since the variable is all by itself, but if you were to print something like "{$a},000,000 mln dollars", then you definitely need to use the braces.
4. How do you define a constant? - Via define() directive, like define ("MYCONSTANT", 100);
5. How do you pass a variable by value? - Just like in C++, put an ampersand in front of it, like $a = &$b
6. Will comparison of string "10" and integer 11 work in PHP? - Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared.
7. When are you supposed to use endif to end the conditional statement? - When the original if was followed by : and then the code block without braces.
8. Explain the ternary conditional operator in PHP? - Expression preceding the ? is evaluated, if it’s true, then the expression preceding the : is executed, otherwise, the expression following : is executed.
9. How do I find out the number of parameters passed into function? - func_num_args() function returns the number of parameters passed in.
10. If the variable $a is equal to 5 and variable $b is equal to character a, what’s the value of $$b? - 100, it’s a reference to existing variable.
11. What’s the difference between accessing a class method via -> and via ::? - :: is allowed to access methods that can perform static operations, i.e. those, which do not require object initialization.
12. Are objects passed by value or by reference? - Everything is passed by value.
13. How do you call a constructor for a parent class? - parent::constructor($value)
14. What’s the special meaning of __sleep and __wakeup? - __sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.
15. Why doesn’t the following code print the newline properly?
    Because inside the single quotes the n character is not interpreted as newline, just as a sequence of two characters - and n.
16. Would you initialize your strings with single quotes or double quotes? - Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.
17. How come the code works, but doesn’t for two-dimensional array of mine? - Any time you have an array with more than one dimension, complex parsing syntax is required. print "Contents: {$arr[1][2]}" would’ve worked.
18. What is the difference between characters �23 and x23? - The first one is octal 23, the second is hex 23.
19. With a heredoc syntax, do I get variable substitution inside the heredoc contents? - Yes.
20. I want to combine two variables together:
    

     $var1 = 'Welcome to ';
    $var2 = 'TechInterviews.com';

21. 
    What will work faster? Code sample 1:
    

    $var 3 = $var1.$var2;
    

    Or code sample 2:
    
    

    $var3 = "$var1$var2";
    

    Both examples would provide the same result - $var3 equal to "Welcome to TechInterviews.com". However, Code Sample 1 will work significantly faster. Try it out with large sets of data (or via concatenating small sets a million times or so), and you will see that concatenation works significantly faster than variable substitution.
    
22. For printing out strings, there are echo, print and printf. Explain the differences. - 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:
    
    and it will output the string "Welcome to TechInterviews!" 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.
    
23. 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? - On large strings that need to be formatted according to some length specifications, use wordwrap() or chunk_split().
24. What’s the output of the ucwords function in this example?
    

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

    What will be printed is TECHINTERVIEWS IS COLLECTION OF INTERVIEW QUESTIONS.
    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.
    
25. What’s the difference between htmlentities() and htmlspecialchars()? - htmlspecialchars only takes care of <, >, single quote ‘, double quote " and ampersand. htmlentities translates all occurrences of character sequences that have different meaning in HTML.
26. What’s the difference between md5(), crc32() and sha1() crypto on PHP? - The major difference is the length of the hash generated. CRC32 is, evidently, 32 bits, while sha1() returns a 128 bit value, and md5() returns a 160 bit value. This is important when avoiding collisions.
27. So if md5() generates the most secure hash, why would you ever use the less secure crc32() and sha1()? - 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.