Deleting characters matching a pattern

PHP:
Deleting characters matching a pattern

How to:

PHP uses the preg_replace function to delete characters that match a pattern using regular expressions. Here’s how to strip digits from a string:

<?php
$text = "Year 2023!";
$pattern = '/\d+/'; // Pattern to match all digits
$result = preg_replace($pattern, '', $text);
echo $result; // Outputs: Year !
?>

And here’s how to remove whitespace:

<?php
$text = "Too   many      spaces!";
$pattern = '/\s+/'; // Pattern to match all whitespace
$result = preg_replace($pattern, ' ', $text);
echo $result; // Outputs: Too many spaces!
?>

Deep Dive

Deleting characters by matching patterns isn’t new. PHP’s preg_replace function, which powers this functionality, uses Perl-compatible regular expressions, a staple of text processing since Perl’s rise in the late ’80s. Alternatives to preg_replace include str_replace for simple replacements and trim, ltrim, and rtrim for removing whitespaces from strings. For more nuanced pattern deletions, preg_replace_callback can be used for additional control during the replacement process.

It’s useful to know that the PREG in preg_replace stands for Perl Regular Expressions, signifying PHP’s usage of Perl’s pattern syntax. Here’s the breakdown:

\d matches any digit. Adding + means “one or more” of the preceding element (digits, in this case).
\s finds any whitespace. Like numbers, + after \s targets long stretches of space.

Choosing between preg_replace and its alternatives depends on what you’re doing. Use preg_replace for complicated patterns and str_replace when dealing with simple, direct substitutions.

Remember, misuse of regular expressions can lead to inefficient code. Always benchmark and use regular expressions smartly.

PHP:Deleting characters matching a pattern

How to:

Deep Dive

See Also

PHP:
Deleting characters matching a pattern