PHP Interview Questions - Set 4 - PHP Interview Questions - dyclassroom

This page contains PHP interview questions and answers.

Q1: Name the programming languages PHP resembles

PHP resembles Perl and C programming language.

Q2: What is the difference between `print` and `echo` in PHP?

Both echo and print are language construct and not a function and both are used to print output.

But they have the following differences.

echo returns no value while print returns 1
echo can take multiple arguments while print can take one argument.

Q3: Write two ways of creating a constant `PI` and set the value to `3.14` in PHP

We can create constants in the following two ways.

Using the define() function
Using the const keyword

In the following code we are creating the PI constant using the define function.

define('PI', 3.14);

In the following code we are creating the PI constant using the const keyword.

const PI = 3.14;

Q4: Write PHP code to print the content of an associative array

In the following example we have an associative array $assocArr and we are printing its content using the foreach loop.

$assocArr = array(
  'firstname' => 'Yusuf',
  'lastname' => 'Shakeel',
  'youtube' => 'https://www.youtube.com/yusufshakeel'
);

foreach ($assocArr as $key => $value) {
  echo "<p>{$key} : {$value}</p>";
}

Q5: What is the use of `isset` function?

We use the isset function to check if a variable is defined and has a value other than NULL.

Q6: What will be the output of the following PHP code?

PHP Code:

$x = null;
isset($x);

Answer: false as $x is set to NULL and isset returns false if value is NULL.

$x = "Hello World";
unset($x);
isset($x);

Answer: false as $x was unset.

Q7: What is the difference between `$x` and `$$x` in PHP?

$x is a variable whereas, $$x is a variable of variable.

Example:

$x = 'a';
$$x = 20;
echo $x . ' ' . ${$x} . ' ' . $a;

Output: a 20 20.

In the above code we have a variable $x which is assigned value a.

$$x means $a as $x holds value a. So, we are assigning value 20 to $a.

In the last line we are printing all the value.

Q8: What are magic constants in PHP?

Magic constants are predefined constants which starts and ends with double underscore (__).

Following are some of the magic constants.

__LINE__
__FUNCTION__
__CLASS__
__FILE__
__METHOD__

Q9: What are the different ways of creating comment in PHP?

We can create single line comments as follows.

Using //
Using #

We can create multi line comments using /* and */.

Q10: How will you create variable length argument function in PHP?

To create variable length argument function in PHP we have to use three dots like the following.

function foo(...$args) {
  // some code goes here
}

PHP Interview Questions - Set 4