PHP - Manual: strnatcmp

2024-12-22

strncasecmp »

« strnatcasecmp

strnatcmp

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

strnatcmp — 使用自然排序算法比较字符串

说明

strnatcmp(string $str1, string $str2): int

该函数实现了以人类习惯对数字型字符串进行排序的比较算法，这就是“自然顺序”。注意该比较区分大小写。

参数

str1: 第一个字符串。
str2: 第二个字符串。

返回值

与其他字符串比较函数类似，如果 str1 小于 str2 返回 < 0；如果 str1 大于 str2 返回 > 0；如果两者相等，返回 0。

范例

下面的例子展示了该算法与计算机常规字符串比较算法（ strcmp() 所使用的）的区别：


<?php
$arr1 = $arr2 = array("img12.png", "img10.png", "img2.png", "img1.png");
echo "Standard string comparison\n";
usort($arr1, "strcmp");
print_r($arr1);
echo "\nNatural order string comparison\n";
usort($arr2, "strnatcmp");
print_r($arr2);
?>

以上例程会输出：

Standard string comparison
Array
(
    [0] => img1.png
    [1] => img10.png
    [2] => img12.png
    [3] => img2.png
)

Natural order string comparison
Array
(
    [0] => img1.png
    [1] => img2.png
    [2] => img10.png
    [3] => img12.png
)

更多信息，参见：Martin Pool 的» 自然顺序的字符串比较 page.

参见

preg_match() - 执行匹配正则表达式
strcasecmp() - 二进制安全比较字符串（不区分大小写）
substr() - 返回字符串的子串
stristr() - strstr 函数的忽略大小写版本
strcmp() - 二进制安全字符串比较
strncmp() - 二进制安全比较字符串开头的若干个字符
strncasecmp() - 二进制安全比较字符串开头的若干个字符（不区分大小写）
strnatcasecmp() - 使用“自然顺序”算法比较字符串（不区分大小写）
strstr() - 查找字符串的首次出现
natsort() - 用“自然排序”算法对数组排序
natcasesort() - 用“自然排序”算法对数组进行不区分大小写字母的排序

add a note

User Contributed Notes 5 notes

down

in dot games dot mq at gmail dot com ¶

5 years ago


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']);} );

down

thomas at uninet dot se ¶

15 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.

down

-1

chris at ocproducts dot com ¶

5 years ago


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.

down

-3

spamspamspam at gmx dot com ¶

3 years ago


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)

down

-59

Zero ¶

11 years ago


If you want to compare $_SESSION variables to a string use this


<?php

if(isset($_SESSION['usertype']))

{    

     echo "usertype " .$_SESSION['usertype'];

                

     $ut = $_SESSION['usertype'];

                

     if(strnatcmp($ut,"admin"))

     {

          echo "hello admin";

     }

}

?>

add a note

官方地址：https://www.php.net/manual/en/function.strnatcmp.php

有任何技术问题请点击这里网站运营推广招聘

IT PHP 编程语言 Linux 开发编程科技 Elasticsearch HTML/CSS/XML 网络数据库 JAVA 面试 NoSQL C/C++ Golang Git 算法操作系统正则表达式 Redis 互联网 MySql JavaScript 运维软件国际架构设计 Mac OS TCP/IP Excel Vim Windows Socket Oracle VR MongoDB Python 运营 MemCache 商业硬件电子娱乐设计 nginx 摄影游戏 WordPress HTTP 团建数码电器

php7 安装fileinfo扩展 preg_split — 通过一个正则表达式分隔字符串 php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题 [PHP] inet_pton/inet_ntop IP地址转换函数 PHP 8.1 [鸟哥]PHP_INT_MIN 和 -9223372036854775808 adodb手册 ADORecordSet对象 opcache预加载 Composer的Packagist资源 array_multisort() 多字段排序 PHPMailer设置utf8 PHPMailer字符集CharSet mysql面试题 PHP json解析（json_decode）页面工具 [原创]诡异的php-fpm超时问题 php中几种注释规范纯php实现DES以及TripleDES加密算法 php 修改图片大小支持php7的性能采集扩展利用PHP SOAP实现WEB SERVICE

略微加速

PHP官方手册 - 互联网笔记

strnatcmp

说明

参数

返回值

范例

参见

User Contributed Notes 5 notes