PHP Manual
String Functions
Binary safe comparison of two strings from an offset, up to length characters

substr_compare

(PHP 5, PHP 7)

substr_compare — Binary safe comparison of two strings from an offset, up to length characters

Description

substr_compare ( string $haystack , string $needle , int $offset [, int|null $length = NULL [, bool $case_insensitive = FALSE ]] ) : int

substr_compare() compares haystack from position offset with needle up to length characters.

Parameters

haystack: The main string being compared.
needle: The secondary string being compared.
offset: The start position for the comparison. If negative, it starts counting from the end of the string.
length: The length of the comparison. The default value is the largest of the length of the needle compared to the length of haystack minus the offset.
case_insensitive: If case_insensitive is TRUE, comparison is case insensitive.

Return Values

Returns < 0 if haystack from position offset is less than needle, > 0 if it is greater than needle, and 0 if they are equal. If offset is equal to (prior to PHP 7.2.18, 7.3.5) or greater than the length of haystack, or the length is set and is less than 0, substr_compare() prints a warning and returns FALSE.

Changelog

Version	Description
8.0.0	`length` is nullable now.
7.2.18, 7.3.5	`offset` may now be equal to the length of `haystack`.

Examples

Example #1 A substr_compare() example

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

Php/docs/function.substr-compare

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