PHP 7.0.6 Released

    strnatcmp

    (PHP 4, PHP 5, PHP 7)

    strnatcmp — String comparisons using a "natural order" algorithm

    Description

    int strnatcmp ( string $str1 , string $str2 )

    This function implements a comparison algorithm that orders alphanumeric strings in the way a human being would, this is described as a "natural ordering". Note that this comparison is case sensitive.

    Parameters

    str1

    The first string.

    str2

    The second string.

    Return Values

    Similar to other string comparison functions, this one returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal.

    Examples

    An example of the difference between this algorithm and the regular computer string sorting algorithms (used in strcmp()) can be seen below:

    <?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);
    ?>

    The above example will output:

    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
)
    For more information see: Martin Pool's » Natural Order String Comparison page.

    See Also

    • preg_match() - Perform a regular expression match
    • strcasecmp() - Binary safe case-insensitive string comparison
    • substr() - Return part of a string
    • stristr() - Case-insensitive strstr
    • strcmp() - Binary safe string comparison
    • strncmp() - Binary safe string comparison of the first n characters
    • strncasecmp() - Binary safe case-insensitive string comparison of the first n characters
    • strnatcasecmp() - Case insensitive string comparisons using a "natural order" algorithm
    • strstr() - Find the first occurrence of a string
    • natsort() - Sort an array using a "natural order" algorithm
    • natcasesort() - Sort an array using a case insensitive "natural order" algorithm

    User Contributed Notes

    thomas at uninet dot se
    9 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.
    Zero
    5 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";
         }
    }
    ?>
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