PHP Interview Questions and Answers

Ques 1. What does a special set of tags <?= and ?> do in PHP?

The output is displayed directly to the browser.

Ques 2. 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.

Ques 3. How do you define a constant?

Via define() directive, like define ("MYCONSTANT", 100);

Ques 4. How do you pass a variable by value?

Just like in C++, put an ampersand in front of it, like $a = &$b

Ques 5. 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.

Ques 6. 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.
E.g $id = isset($_GET['id']) ? $_GET['id'] : false;

Ques 7. How do you call a constructor for a parent class?

parent::constructor($value)

Ques 8. Why doesn't the following code print the newline properly?                 $str = 'Hello, there.nHow are you?
            print $str;
    ?>

Because inside the single quotes the n character is not interpreted as newline, just as a sequence of two characters - and n.

Ques 9. 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.

Ques 10. What is the difference between characters 23 and x23?

The first one is octal 23, the second is hex 23.

Ques 11. I want to combine two variables together:

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

$var 3 = $var1.$var2;

$var3 = "$var1$var2";