Previously, it was possible for the number_format function to return -0. Whilst this is perfectly valid according to the IEEE 754 floating point specification, this oddity was not desirable for displaying formatted numbers in a human-readable form. Numeric keys are now better handled when casting arrays to objects and objects to arrays (either from explicit casting or by settype). This means that integer (or stringy integer) keys from arrays being casted to objects are now accessible: 1]; $obj = (object)$arr; var_dump( $obj, $obj->{'0'}, // now accessible $obj->{0} // now accessible ); ]]> &example.outputs; // string key now, rather than integer key int(1) } int(1) int(1) ]]> And integer (or stringy integer) keys from objects being casted to arrays are now accessible: {0} = 1; } }; $arr = (array)$obj; var_dump( $arr, $arr[0], // now accessible $arr['0'] // now accessible ); ]]> &example.outputs; // integer key now, rather than string key int(1) } int(1) int(1) ]]> Previously, passing &null; to the get_class function would output the name of the enclosing class. This behaviour has now been removed, where an E_WARNING will be output instead. To achieve the same behaviour as before, the argument should simply be omitted. An E_WARNING will now be emitted when attempting to count non-countable types (this includes the sizeof alias function). &example.outputs; As part of the long-term migration away from resources, the Hash extension has been updated to use objects instead of resources. The change should be seamless for PHP developers, except for where is_resource checks have been made (which will need updating to is_object instead). The following changes to the defaults have been made: tls:// now defaults to TLSv1.0 or TLSv1.1 or TLSv1.2 ssl:// an alias of tls:// STREAM_CRYPTO_METHOD_TLS_* constants default to TLSv1.0 or TLSv1.1 + TLSv1.2, instead of TLSv1.0 only Previously, using gettype on a closed resource would return a string of "unknown type". Now, a string of "resource (closed)" will be returned. Previously, using is_object on the __PHP_Incomplete_Class class would return &false;. Now, &true; will be returned. Unqualified references to undefined constants will now generate an E_WARNING (instead of an E_NOTICE). In the next major version of PHP, they will generate Error exceptions. The officially supported, minimum Windows versions are now Windows 7/Server 2008 R2. Compatibility checks upon default trait property values will no longer perform casting. The object name was previously soft-reserved in PHP 7.0. This is now hard-reserved, prohibiting it from being used as a class, trait, or interface name. Support for NetWare has now been removed. While array_unique with SORT_STRING formerly copied the array and removed non-unique elements (without packing the array afterwards), now a new array is built by adding the unique elements. This can result in different numeric indexes. The bcmod function no longer truncates fractional numbers to integers. As such, its behavior now follows fmod, rather than the % operator. For example bcmod('4', '3.5') now returns 0.5 instead of 1. The hash_hmac, hash_hmac_file, hash_pbkdf2, and hash_init (with HASH_HMAC) functions no longer accept non-cryptographic hashes. The json_decode function option, JSON_OBJECT_AS_ARRAY, is now used if the second parameter (assoc) is &null;. Previously, JSON_OBJECT_AS_ARRAY was always ignored. Sequences generated by rand and mt_rand for a specific seed may differ from PHP 7.1 on 64-bit machines (due to the fixing of a modulo bias bug in the implementation). The sql.safe_mode ini setting has now been removed. The zone element of the array returned by date_parse and date_parse_from_format represents seconds instead of minutes now, and its sign is inverted. For instance -120 is now 7200. As of PHP 7.2.34, the names of incoming cookies are no longer url-decoded for security reasons.