PHP fnmatch Function
PHP fnmatch function tutorial shows how to match filenames against patterns in PHP. Learn fnmatch with practical examples.
PHP fnmatch Function
last modified April 3, 2025
The PHP fnmatch function checks if a string matches a shell wildcard pattern. It’s useful for filename matching and pattern validation.
Basic Definition
The fnmatch function tests if a string matches a given pattern. It supports wildcards like *, ?, and character ranges like [a-z].
Syntax: fnmatch(string $pattern, string $string, int $flags = 0): bool. The function returns true if the string matches the pattern, false otherwise.
Basic fnmatch Example
This shows the simplest usage of fnmatch with a wildcard pattern.
basic_fnmatch.php
<?php
declare(strict_types=1);
$result = fnmatch("*.txt", “document.txt”);
var_dump($result); // Outputs: bool(true)
This checks if “document.txt” matches the “*.txt” pattern. The * wildcard matches any sequence of characters, so any .txt file will match.
Question Mark Wildcard
The ? wildcard matches exactly one character in the pattern.
question_mark.php
<?php
declare(strict_types=1);
$result1 = fnmatch(“file?.txt”, “file1.txt”); $result2 = fnmatch(“file?.txt”, “file12.txt”);
var_dump($result1); // Outputs: bool(true) var_dump($result2); // Outputs: bool(false)
The first example matches because ? matches the single “1”. The second fails because ? can’t match two characters. Each ? must match exactly one character.
Character Ranges
Square brackets define character ranges that match any single character within.
character_ranges.php
<?php
declare(strict_types=1);
$result1 = fnmatch(“image_[0-9].jpg”, “image_1.jpg”); $result2 = fnmatch(“image_[0-9].jpg”, “image_a.jpg”);
var_dump($result1); // Outputs: bool(true) var_dump($result2); // Outputs: bool(false)
The [0-9] range matches any single digit. The first example matches because “1” is in the range. The second fails because “a” isn’t a digit.
Case Insensitive Matching
The FNM_CASEFOLD flag makes the matching case insensitive.
case_insensitive.php
<?php
declare(strict_types=1);
$result = fnmatch("*.TXT", “document.txt”, FNM_CASEFOLD);
var_dump($result); // Outputs: bool(true)
Without the flag, this would return false due to case mismatch. With FNM_CASEFOLD, the pattern matches regardless of case differences in the filename.
Directory Matching
fnmatch can match paths with directory separators.
directory_matching.php
<?php
declare(strict_types=1);
$result = fnmatch("/var/www/*.php", “/var/www/index.php”);
var_dump($result); // Outputs: bool(true)
This checks if the full path matches the pattern. The * wildcard matches the “index” portion of the path. The function treats / characters literally in patterns.
Best Practices
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Pattern Clarity: Use simple patterns when possible.
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Performance: Complex patterns can be slow on large inputs.
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Security: Validate inputs when used in security contexts.
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Testing: Test edge cases with unusual filenames.
Source
This tutorial covered the PHP fnmatch function with practical examples showing pattern matching in different scenarios.
Author
My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.
