Preg_split for splitting in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the preg_split function do in PHP?

preg_split splits a string into pieces using a regular expression as the separator.

beginner

How do you use preg_split to split a string by commas and spaces?

Use a pattern like /[ ,]+/ to split by one or more commas or spaces.

Example: preg_split('/[ ,]+/', 'apple, banana orange') splits into ['apple', 'banana', 'orange'].

intermediate

What is the difference between explode and preg_split?

explode splits a string by a fixed string separator.

preg_split splits by a pattern, allowing more flexible splitting like multiple separators or patterns.

intermediate

What does the PREG_SPLIT_NO_EMPTY flag do in preg_split?

This flag removes empty strings from the result array after splitting.

It helps avoid empty pieces when separators are next to each other.

beginner

Write a simple PHP code snippet using preg_split to split a sentence by spaces.

<?php
$sentence = 'Hello world from PHP';
$words = preg_split('/\s+/', $sentence);
print_r($words);
?>

This splits the sentence into words by one or more spaces.

What kind of argument does preg_split use to split a string?

A A regular expression pattern

B A fixed string separator

C An integer index

D A callback function

preg_split uses a regular expression pattern to decide where to split the string.

Which flag removes empty strings from the result of preg_split?

A PREG_SPLIT_DELIM_CAPTURE

B PREG_SPLIT_OFFSET_CAPTURE

C PREG_SPLIT_NO_EMPTY

D PREG_SPLIT_REMOVE_EMPTY

PREG_SPLIT_NO_EMPTY removes empty strings from the split results.

What will preg_split('/,/', 'a,b,,c') return without flags?

A ['a', 'b', '', 'c']

B ['a', 'b', 'c']

C ['a,b,,c']

D ['a', '', 'b', 'c']

It splits at commas, so the empty string between two commas is included.

Which function is simpler but less flexible than preg_split for splitting strings?

A implode

B str_replace

C substr

D explode

explode splits by a fixed string, not by patterns.

What does the pattern /\s+/ match in preg_split?

A One or more letters

B One or more whitespace characters

C One or more digits

D One or more commas

\s means whitespace, and + means one or more.

Explain how preg_split works and when you would use it instead of explode.

Think about splitting by spaces and commas together.

Describe the purpose of the PREG_SPLIT_NO_EMPTY flag and give an example scenario.

Imagine splitting 'a,,b' by comma.