substr_compare - So sánh nhị phân 2 strings từ vị trí offset, tới độ dài ký tự

substr_compare

(PHP 5)

Description

int substr_compare ( string $main_str , string $str , int $offset [, int $length= 0 [, bool $case_insensitivity= false ]] )

substr_compare() compares main_str from position offset with str up to length characters.

Parameters

offset: The start position for the comparison. If negative, it starts counting from the end of the string.
length: The length of the comparison.
case_insensitivity: If case_insensitivity is TRUE, comparison is case insensitive.

Return Values

Returns < 0 if main_str from position offset is less than str , > 0 if it is greater than str , and 0 if they are equal. If length is equal or greater than length of main_str and length is set, substr_compare() prints warning and returns FALSE.

Changelog

Version	Description
5.1.0	Added the possibility to use a negative `offset` .

Examples

Example #1 A substr_compare() example

 <?php
echo substr_compare("abcde", "bc", 1, 2); // 0
echo substr_compare("abcde", "de", -2, 2); // 0
echo substr_compare("abcde", "bcg", 1, 2); // 0
echo substr_compare("abcde", "BC", 1, 2, true); // 0
echo substr_compare("abcde", "bc", 1, 3); // 1
echo substr_compare("abcde", "cd", 1, 2); // -1
echo substr_compare("abcde", "abc", 5, 1); // warning
?>

User Contributed Notes
substr_compare

sleek
23-May-2005 12:07

 Modified version of the original posted function. Use this one:
 
 <?php
 if (!function_exists('substr_compare')) {
 function substr_compare($main_str, $str, $offset, $length = NULL, $case_insensitivity = false) {
 $offset = (int) $offset;
 
 // Throw a warning because the offset is invalid
 if ($offset >= strlen($main_str)) {
 trigger_error('The start position cannot exceed initial string length.', E_USER_WARNING);
 return false;
 }
 
 // We are comparing the first n-characters of each string, so let's use the PHP function to do it
 if ($offset == 0 && is_int($length) && $case_insensitivity === true) {
 return strncasecmp($main_str, $str, $length);
 }
 
 // Get the substring that we are comparing
 if (is_int($length)) {
 $main_substr = substr($main_str, $offset, $length);
 $str_substr = substr($str, 0, $length);
 } else {
 $main_substr = substr($main_str, $offset);
 $str_substr = $str;
 }
 
 // Return a case-insensitive comparison of the two strings
 if ($case_insensitivity === true) {
 return strcasecmp($main_substr, $str_substr);
 }
 
 // Return a case-sensitive comparison of the two strings
 return strcmp($main_substr, $str_substr);
 }
 }
 ?>