# RFC: Base Convert improvements - Status: Implemented (PHP 7.4) - Authors: Scott Dutton,php@exussum.co.uk - Date: 2019-05-15 - Version: 0.1 - Original: https://wiki.php.net/rfc/base_convert_improvements - Page: https://externals.io/rfc/base_convert_improvements - More for agents: search with https://externals.io/search.md?q={query} · RFCs at https://externals.io/rfc.md · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt ## Votes ### Raise deprecated error in 7.4 and raise to exception in PHP 8 for unknown characters (closed) Yes: 28 · No: 1 Voters: ashnazg (Yes), carusogabriel (Yes), cmb (Yes), cpriest (Yes), danack (Yes), daverandom (Yes), derick (Yes), emir (Yes), galvao (Yes), gasolwu (Yes), girgias (Yes), jasny (Yes), jhdxr (Yes), kalle (Yes), kguest (Yes), mariano (Yes), mbeccati (Yes), mcmic (Yes), mike (Yes), narf (Yes), nikic (Yes), petk (Yes), pollita (Yes), ramsey (Yes), rasmus (Yes), salathe (No), sergey (Yes), stas (Yes), yunosh (Yes) ### Allow negative numbers to be converted in PHP 8 (closed) Yes: 2 · No: 17 Voters: ashnazg (No), carusogabriel (No), daverandom (No), derick (No), emir (No), galvao (No), girgias (Yes), jasny (Yes), kalle (No), kguest (No), mariano (No), mbeccati (No), mike (No), petk (No), pollita (No), ramsey (No), salathe (No), sergey (No), stas (No) ## Discussions on the mailing list - [\[RFC\] Base convert changes](https://externals.io/message/105740.md) — started on 2019-05-18, 8 messages - [\[RFC\] \[Vote\] Base convert changes](https://externals.io/message/105980.md) — started on 2019-06-19, 12 messages - [base_convert should throw a ValueError on characters not valid in number base](https://externals.io/message/131448.md) — started on 2026-06-22, 2 messages - [\[RFC\] Throw ValueError for invalid characters in number base functions](https://externals.io/message/132379.md) — started on 2026-08-28, 15 messages --- ## Introduction The base\_convert family of functions(base\_convert, binhex, hexbin etc) are very accepting with their input arguments, you can pass any string to to them and they give a best effort of converting it. For example base\_convert(“hello world”, 16, 10); will return 237 with no warnings. What this does internally is base\_convert(“ed”, 16, 10); Also negative numbers simply do not work, eg base\_convert(“-ff”, 16, 10); will return 255. (similar to above the “-” gets silently ignored). Experienced developers get caught out by this for example In this case literal binary data was the input and the result was 0 (which is expected but not clear) Other functions affected by this are: - decbin() - Decimal to binary - bindec() - Binary to decimal - decoct() - Decimal to octal - octdec() - Octal to decimal - dechex() - Decimal to hexadecimal - hexdec() - Hexadecimal to decimal Other programming languages behave in a a similar way to this proposal \* Javascript - \* Python - \* Go - Javascript does work with larger numbers correctly, Python and Go work in a way which would be similar to PHP if this change was made. ## Proposal I propose two changes to the base\_convert family of functions. #### Error on ignored characters When passed arguments that base\_convert will ignore, also give a warning to the user informing them their input was incorrect. There is an exception in place for the second char, if base is 16 'x' is allowed eg “0xff”, base 2 allows b and base 8 allows o. this fits in with common formats for these numbers This can be raised to a full exception for a later PHP version (eg PHP 8) #### Allow negative arguments Negative numbers should be allowed to be passed to the base\_convert family of functions. for example base\_convert('-ff', 16', 10); should return -255. Currently users need to make an exception in this case ## Backward Incompatible Changes #### Error on ignored characters No BC breaks for a warning, in the case of an exception there will be a BC break - Would suggest PHP 8 for this. #### Allow negative arguments base\_convert currently in the backend has a zend\_ulong as its representation. We would need a zend\_long. This will change the behavior of numbers in the range 9223372036854775807 - 18446744073709551615 but will allow negative numbers. This currently breaks a fair amount of unit tests that I will need to update if this change is accepted. The unit tests are around extreme values. A secondary BC change would be people who have worked around this in userland code for example This change will break these work arounds Would suggest PHP8 for this change ## Proposed PHP Version(s) PHP 7.4 for warnings PHP 8.0 for negative arguments and exceptions ## RFC Impact ### To SAPIs None ### To Existing Extensions None ### To Opcache None ### New Constants None ### php.ini Defaults ## Open Issues Make sure there are no open issues when the vote starts! ## Unaffected PHP Functionality Only the base\_convert family of functions will be changed ## Future Scope Allow base\_convert to allow any length input and not be restricted to a 64 bit int type ## Proposed Voting Choices 2 votes #### Error on ignored characters This vote will be to raise a E\_DEPRECATED warning for PHP 7.4. Raising to be an InvalidArgumentException in PHP 8 #### Allow negative arguments This vote will allow negative arguments in PHP 8 ## Patches and Tests ## Vote Started 19th June 2019. Ends 3rd July 2019 **Vote: Raise deprecated error in 7.4 and raise to exception in PHP 8 for unknown characters** — Yes: 28 · No: 1 (closed) **Vote: Allow negative numbers to be converted in PHP 8** — Yes: 2 · No: 17 (closed) ## References ## Rejected Features Keep this updated with features that were discussed on the mail lists.