(PHP 4, PHP 5, PHP 7, PHP 8)
strnatcmp — Comparaison de chaînes avec l'algorithme d'"ordre naturel"
Implémente l'algorithme de comparaison qui ordonne les chaînes tel qu'un homme le ferait. Notez que cette comparaison est sensible à la casse.
string1La première chaîne.
string2La seconde chaîne.
De la même façon que les autres fonctions comparant deux chaînes,
la fonction retourne -1 si string1
est inférieure à string2; 1 si string1
est supérieure à string2, et 0 si les deux chaînes
sont égales.
| Version | Description |
|---|---|
| 8.2.0 |
Cette fonction retourne désormais -1 ou 1,
alors qu'auparavant elle renvoyait un nombre négatif ou positif.
|
Un exemple de la différence de traitement avec l'algorithme standard est présenté ci-dessous :
<?php
$arr1 = $arr2 = array("img12.png", "img10.png", "img2.png", "img1.png");
echo "Tri de chaînes standard\n";
usort($arr1, "strcmp");
print_r($arr1);
echo "\nTri de chaînes \"ordre naturel\"\n";
usort($arr2, "strnatcmp");
print_r($arr2);
?>L'exemple ci-dessus va afficher :
Tri de chaînes standard
Array
(
[0] => img1.png
[1] => img10.png
[2] => img12.png
[3] => img2.png
)
Tri de chaînes "ordre naturel"
Array
(
[0] => img1.png
[1] => img2.png
[2] => img10.png
[3] => img12.png
)
Natural Order String
Comparison de Martin Pool (en anglais).
Can also be used with combination of a compare for an array nested value, like
<?php
$array = array(
"city" => "xyz",
"names" => array(
array(
"name" => "Ana2",
"id" => 1
) ,
array(
"name" => "Ana1",
"id" => 2
)
)
);
usort($array["names"], function ($a, $b) { return strnatcmp($a['name'], $b['name']);} );There seems to be a bug in the localization for strnatcmp and strnatcasecmp. I searched the reported bugs and found a few entries which were up to four years old (but the problem still exists when using swedish characters).
These functions might work instead.
<?php
function _strnatcasecmp($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.This function has some interesting behaviour on strings consisting of mixed numbers and letters.
One may expect that such a mixed string would be treated as alpha-numeric, but that is not true.
var_dump(strnatcmp('23','123')); →
int(-1)
As expected, 23<123 (even though first digit is higher, overall number is smaller)
var_dump(strnatcmp('yz','xyz')); →
int(1)
As expected, yz>xyz (string comparison, irregardless of string length)
var_dump(strnatcmp('2x','12y')); →
int(-1)
Remarkable, 2x<12y (does a numeric comparison)
var_dump(strnatcmp('20x','12y'));
int(1)
Remarkable, 20x>12y (does a numeric comparison)
It seems to be splitting what is being compared into runs of numbers and letters, and then comparing each run in isolation, until it has an ordering difference.Some more remarkable outcomes:
var_dump(strnatcmp("0.15m", "0.2m"));
int(1)
var_dump(strnatcmp("0.15m", "0.20m"));
int(-1)
It's not about localisation:
var_dump(strnatcmp("0,15m", "0,2m"));
int(1)
var_dump(strnatcmp("0,15m", "0,20m"));
int(-1)