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

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

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(PHP 5, PHP 7, PHP 8)

substr_compareBinary safe comparison of two strings from an offset, up to length characters


    string $haystack,
    string $needle,
    int $offset,
    ?int $length = null,
    bool $case_insensitive = false
): int

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



The main string being compared.


The secondary string being compared.


The start position for the comparison. If negative, it starts counting from the end of the string.


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.


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.


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.


Example #1 A substr_compare() example

echo substr_compare("abcde""bc"12); // 0
echo substr_compare("abcde""de", -22); // 0
echo substr_compare("abcde""bcg"12); // 0
echo substr_compare("abcde""BC"12true); // 0
echo substr_compare("abcde""bc"13); // 1
echo substr_compare("abcde""cd"12); // -1
echo substr_compare("abcde""abc"51); // warning

See Also

  • strncmp() - Binary safe string comparison of the first n characters

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