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<?php function test($array) { try { return is_indexed_array($array); } catch (Exception $e) { echo $e->getMessage(); return 'error'; } } // non-array - adjust according to your preferred error handling technique assert(test(null) === false); assert(test(false) === false); assert(test(new stdClass) === false); // empty array assert(test([]) === true); // numeric keys assert(test([null, 'a', 'b']) === true); // proper indexed array; also, to catch wrong isset usage assert(test([1 => 'a', 2 => 'b', 3 => 'c']) === false); // sequential but not 0-based assert(test([-1 => '', 0 => '', 1 => 'a']) === false); // sequential but not 0-based assert(test([0 => '', 2 => 'b', 3 => 'c']) === false); // 1 index missing assert(test([0 => '', 2 => 'b', 1 => 'a']) === false); // numeric but unordered assert(test([0 => '']) === true); // single item assert(test([1 => 'a']) === false); // single item assert(test([NAN]) === true); assert(test([NAN => '']) === false); assert(test([INF]) === true); assert(test([INF => '']) === false); // string keys assert(test(['' => '', 'a' => 'a', 'b' => 'b']) === false); // proper associative array assert(test(['' => '']) === false); // single item; also, associative even though '' == 0 // mixed keys assert(test(['' => '', 1 => 'a']) === false); // first key string but rest not assert(test(['' => '', 0 => '']) === false); // first key string but rest not assert(test([0 => '', 'a' => 'a']) === false); // first key numeric but rest not // numeric string keys assert(test([' 0' => '']) === false); // associative even though ' 0' == 0 assert(test(['00' => '']) === false); // associative even though '00' == 0 assert(test(['0*' => '']) === false); // associative even though '0*' == 0 assert(test(['0.0' => '']) === false); // associative even though '0.0' == 0.0 assert(test(['0x0' => '']) === false); // associative even though '0x0' == 0 assert(test(['0e0' => '']) === false); // associative even though '0e0' == 0 $obj = new stdClass; $obj->{0} = ''; assert(test((array)$obj) === false); // to catch ['0' => ''] like situations function is_indexed_array(&$array) { if (!is_array($array)) return false; $i = -1; foreach ($array as $k => $v) if ($k !== ++$i) return false; return $i === -1; }
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
Fatal error: Uncaught AssertionError: assert(test([null, 'a', 'b']) === true) in /in/iZIm9:29 Stack trace: #0 /in/iZIm9(29): assert(false, 'assert(test([nu...') #1 {main} thrown in /in/iZIm9 on line 29
Process exited with code 255.
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33
Warning: assert(): assert(test([null, 'a', 'b']) === true) failed in /in/iZIm9 on line 29 Warning: assert(): assert(test([0 => '']) === true) failed in /in/iZIm9 on line 34 Warning: assert(): assert(test([NAN]) === true) failed in /in/iZIm9 on line 36 Warning: assert(): assert(test([INF]) === true) failed in /in/iZIm9 on line 38
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28
Warning: assert(): Assertion failed in /in/iZIm9 on line 29 Warning: assert(): Assertion failed in /in/iZIm9 on line 34 Warning: assert(): Assertion failed in /in/iZIm9 on line 36 Warning: assert(): Assertion failed in /in/iZIm9 on line 38

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