? PHP String Compare Functions

? Quick Overview

PHP provides multiple built-in functions to compare strings. These functions help determine whether strings are equal, or which string is greater or smaller. They differ based on case sensitivity and comparison logic.

?️ Key Concepts

• strcmp() – Case-sensitive comparison.
• strcasecmp() – Case-insensitive comparison.
• strnatcmp() – Natural order comparison (case-sensitive).
• strnatcasecmp() – Natural order comparison (case-insensitive).

? Syntax & Theory

All string comparison functions return an integer:

• 0 → Strings are equal
• < 0 → First string is smaller
• > 0 → First string is larger

? Example 1: strcmp()

// Case-sensitive string comparison
<?php
$string1 = "Hello";
$string2 = "hello";
$result = strcmp($string1, $string2);
echo $result;
?>

? Example 2: strcasecmp()

// Case-insensitive string comparison
<?php
$string1 = "Hello";
$string2 = "hello";
$result = strcasecmp($string1, $string2);
echo $result;
?>

? Example 3: strnatcmp()

// Natural order comparison with numbers
<?php
$string1 = "file10";
$string2 = "file2";
$result = strnatcmp($string1, $string2);
echo $result;
?>

? Example 4: strnatcasecmp()

// Case-insensitive natural order comparison
<?php
$string1 = "file10";
$string2 = "FILE2";
$result = strnatcasecmp($string1, $string2);
echo $result;
?>

? Live Output / Explanation

Natural comparison treats numeric values logically, so file10 is considered greater than file2, unlike normal string comparison.

? Use Cases

• Validating user input
• Sorting filenames and versions
• Search and filtering logic
• Comparing identifiers