(PHP 4, PHP 5, PHP 7)

strnatcmpString comparisons using a "natural order" algorithm


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

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.



The first string.


The second string.

Return Values

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


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

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

The above example will output:

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

Natural order string comparison
    [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

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