Preg_split for splitting in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of preg_split with simple delimiter

What is the output of the following PHP code?

PHP

<?php
$input = "apple,banana,orange";
$result = preg_split('/,/', $input);
print_r($result);
?>

A Array ( [0] => apple,banana,orange )

B Array ( [0] => apple [1] => banana [2] => orange [3] => )

C Array ( [0] => apple [1] => banana,orange )

D Array ( [0] => apple [1] => banana [2] => orange )

💡 Hint

preg_split splits the string where the pattern matches, returning all parts as array elements.

The pattern '/,/' matches commas, so preg_split splits the string at each comma, producing an array of the fruits.

❓ Predict Output

intermediate

preg_split with limit parameter

What is the output of this PHP code?

PHP

<?php
$input = "one,two,three,four";
$result = preg_split('/,/', $input, 3);
print_r($result);
?>

A Array ( [0] => one [1] => two [2] => three,four )

B Array ( [0] => one [1] => two [2] => three [3] => four )

C Array ( [0] => one,two,three [1] => four )

D Array ( [0] => one [1] => two [2] => three [3] => four [4] => )

💡 Hint

The limit parameter controls how many pieces the string is split into.

With limit=3, preg_split splits into at most 3 parts. The last part contains the rest of the string after the second comma.

❓ Predict Output

advanced

preg_split with PREG_SPLIT_NO_EMPTY flag

What is the output of this PHP code?

PHP

<?php
$input = ",apple,,banana,orange,";
$result = preg_split('/,/', $input, -1, PREG_SPLIT_NO_EMPTY);
print_r($result);
?>

A Array ( [0] => [1] => apple [2] => [3] => banana [4] => orange [5] => )

B Array ( [0] => apple [1] => banana [2] => orange )

C Array ( [0] => apple [1] => [2] => banana [3] => orange )

D Array ( [0] => apple,banana,orange )

💡 Hint

The PREG_SPLIT_NO_EMPTY flag removes empty strings from the result.

The input has empty parts between commas. Using PREG_SPLIT_NO_EMPTY removes those empty strings from the output array.

❓ Predict Output

advanced

preg_split with capturing parentheses

What is the output of this PHP code?

PHP

<?php
$input = "red1green2blue3";
$result = preg_split('/(\d)/', $input, -1, PREG_SPLIT_DELIM_CAPTURE);
print_r($result);
?>

A Array ( [0] => red [1] => 1 [2] => green [3] => 2 [4] => blue [5] => 3 )

B Array ( [0] => red1green2blue3 )

C Array ( [0] => red [1] => green [2] => blue )

D Array ( [0] => red [1] => 1green2blue3 )

💡 Hint

PREG_SPLIT_DELIM_CAPTURE includes the parts matched by parentheses in the output.

The pattern captures digits. With PREG_SPLIT_DELIM_CAPTURE, the digits appear as separate elements in the output array.

🧠 Conceptual

expert

Understanding preg_split behavior with complex regex

Given the code below, how many elements will the resulting array have?

PHP

<?php
$input = "a1b2c3d4";
$result = preg_split('/(?<=\d)/', $input);
echo count($result);
?>

A 7

B 8

C 4

D 1

💡 Hint

The regex uses a lookbehind to split after each digit.

The pattern splits the string after each digit, resulting in 4 parts: 'a1', 'b2', 'c3', 'd4'.