strnatcasecmp

(PHP 4, PHP 5, PHP 7, PHP 8)

strnatcasecmpCase insensitive string comparisons using a "natural order" algorithm

Description

strnatcasecmp(string $string1, string $string2): int

This function implements a comparison algorithm that orders alphanumeric strings in the way a human being would. The behaviour of this function is similar to strnatcmp(), except that the comparison is not case sensitive. For more information see: Martin Pool's » Natural Order String Comparison page.

Parameters

string1

The first string.

string2

The second string.

Return Values

Similar to other string comparison functions, this one returns -1 if string1 is less than string2 1 if string1 is greater than string2, and 0 if they are equal.

Changelog

Version Description
8.2.0 This function now returns -1 or 1, where it previously returned a negative or positive number.

Examples

Example #1 strnatcasecmp() example

<?php

var_dump
(strnatcasecmp('Apple', 'Banana'));
var_dump(strnatcasecmp('Banana', 'Apple'));
var_dump(strnatcasecmp('apple', 'Apple'));
?>

The above example will output:

int(-1)
int(1)
int(0)

See Also

  • preg_match() - Perform a regular expression match
  • strcmp() - Binary safe string comparison
  • strcasecmp() - Binary safe case-insensitive string comparison
  • substr() - Return part of a string
  • stristr() - Case-insensitive strstr
  • strncasecmp() - Binary safe case-insensitive string comparison of the first n characters
  • strncmp() - Binary safe string comparison of the first n characters
  • strstr() - Find the first occurrence of a string
  • setlocale() - Set locale information

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User Contributed Notes 3 notes

up
9
chatfielddaniel at googlemail dot com
13 years ago
The function treats '_' as after letters and numbers when it would be placed before logically.
up
2
Marco
8 years ago
Use strnatcmp to avoid the _ problem as mentioned below;

<<  The function treats '_' as after letters and numbers when it would be placed before logically. >>
up
-10
thomas at uninet dot se
18 years ago
There seems to be a bug in the localization for strnatcmp and strnatcasecmp. I searched the reported bugs and found a few entries which were up to four years old (but the problem still exists when using swedish characters).

These functions might work instead.
<?php
function _strnatcasecmp($left, $right) {
  return
_strnatcmp(strtolower($left), strtolower($right));
}

function
_strnatcmp($left, $right) {
  while((
strlen($left) > 0) && (strlen($right) > 0)) {
    if(
preg_match('/^([^0-9]*)([0-9].*)$/Us', $left, $lMatch)) {
     
$lTest = $lMatch[1];
     
$left = $lMatch[2];
    } else {
     
$lTest = $left;
     
$left = '';
    }
    if(
preg_match('/^([^0-9]*)([0-9].*)$/Us', $right, $rMatch)) {
     
$rTest = $rMatch[1];
     
$right = $rMatch[2];
    } else {
     
$rTest = $right;
     
$right = '';
    }
   
$test = strcmp($lTest, $rTest);
    if(
$test != 0) {
      return
$test;
    }
    if(
preg_match('/^([0-9]+)([^0-9].*)?$/Us', $left, $lMatch)) {
     
$lTest = intval($lMatch[1]);
     
$left = $lMatch[2];
    } else {
     
$lTest = 0;
    }
    if(
preg_match('/^([0-9]+)([^0-9].*)?$/Us', $right, $rMatch)) {
     
$rTest = intval($rMatch[1]);
     
$right = $rMatch[2];
    } else {
     
$rTest = 0;
    }
   
$test = $lTest - $rTest;
    if(
$test != 0) {
      return
$test;
    }
  }
  return
strcmp($left, $right);
}
?>

The code is not optimized. It was just made to solve my problem.
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