int strnatcasecmp ( string $str1 , string $str2 )
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.
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.