Interview Questions and Answers

The output is displayed directly to the browser.

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.

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

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

When the original if was followed by : and then the code block without braces.

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;

parent::constructor($value)

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

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.

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

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

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.