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10 questions to solve
Instructions
- This quiz goes to full-screen once you press the Start button.
- At the end of the quiz, you are able to review all the questions that you answered wrong and see their explanations.
What does the following code output?
<?php
$x = 10;
$y = 20;
echo '($x, $y)';A single-quoted string (
'') in PHP can't be interpolated. Hence, the string '($x, $y)' simply yields the output ($x, $y). This goes with choice (B). For more info, refer to PHP Strings — Basics — String interpolation.What does the following code output?
<?php
$x = 10;
$y = 20;
echo "($x, $y)";A double-quoted string (
"") in PHP can be interpolated, which is exactly the case with the string "($x, $y)" — this string yields the output (10, 20). Hence, the correct choice is (A). For more info, refer to PHP Strings — Basics — String interpolation.What does the following code output?
<?php
$x = 0;
$a = [1, 2];
echo "($a[$x], $a[1])";In the string
"($a[$x], $a[1])", $a[$x] is an array element access expression which resolves down to $a[0] and then, ultimately, to 1. A same reasoning applies to $a[1], which resolves down to 2. Hence, the string resolves to the '(1, 2)', and so the correct choice is (A). For more info, refer to PHP Strings — Basics — String interpolation.Which of the following shows a heredoc string in PHP?
A heredoc string in PHP has the following syntax:
<<<identifier
<string_data>
identifierThis aligns with the choices (B) and (C). For more info, refer to PHP Strings — Basics — Heredoc strings.
What is the error in the following code?
<?php
$str = <<<end
The end of string is this.
end;There is absolutely no error in the code. For more info, refer to PHP Strings — Basics — Heredoc strings.
How to convert a string to lowercase characters?
The
strtolower() function in PHP is used to convert a string to lowercase characters. Hence, the correct choice is (B). For more info, refer to PHP Strings — Basics — Changing the casing.How to convert a string to uppercase characters?
The
strtoupper() function in PHP is used to convert a string to uppercase characters. Hence, the correct choice is (B). For more info, refer to PHP Strings — Basics — Changing the casing.What does the function
f(), as shown below, do?<?php
function f($str) {
return $str === strtolower($str);
}The function
f() determines whether the string $str is in lowercase form or not. This goes with choice (A). For more info, refer to PHP Strings — Basics — Changing the casing.Which of the following functions is used to search for a substring in a string?
The only correct choice here is
str_contains() which is used to determine whether a given string contains a particular substring. For more info, refer to PHP Strings — Basics — Searching for a substring.What does the following code output?
<?php
$str = 'Good';
$str[0] = 'H';
echo $str;In PHP, strings are mutable, i.e. a character can be modified by accessing it using bracket notation (similar to how an array element is accessed). In the code above,
$str[0] = 'H' mutates the first character of $str to 'H'. Consequently, $str becomes 'Hood'. The correct choice is, therefore, (B). For more info, refer to PHP Strings — Basics — String mutability.
