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PHP WTF: A PHP Annoyance Posted Every Day
- DougBTX 17y agoOK, I'm stumped, why is this? echo "<?php if (0 == 'test') echo 'true???'; ?>" | php # => "true???"
- daeken 17y agoAs explained under 'read more', it's because 'test' will be cast to a number for comparison. Since 'test' isn't a number, it becomes 0, which is equivalent.
- Sharlin 17y agoWhich is, of course, a deeply broken way to handle the situation. If multi-type comparisons have to be supported at all, at least one ought to cast the narrower type to the wider one! In this case, the int argument ought to be cast to string, because all ints can be uniquely represented as a string, but not the other way around. As it stands, PHP's equality operator is not an equivalence relation because it's not transitive. This is deeply unintuitive and logic-defying.
- encoderer 17y agoI really would find this "deeply unintuitive" if I decided to try PHP with only intellisense as a reference. But by their very definition a language's idioms are not obvious. And this isn't my first rodeo, so I'd know that. And I'd read a little--just a little--before i jumped in. Concepts and algorithms are universal. Operators and keywords are not. Luckily, this is such a common need when learning a language that this information is kept all together in a tidy tabular way. Because without it, I'd probably whip up an index.php and write something like print 'Welcome, ' + user.firstName;, get frustrated by parse errors, then by runtime errors, then write some impassioned comment about how deeply unintuitive it is to require prefixed variables and how using a dot for concatenation instead of a plus sign or ampersand is simply logic defying. And that same table that explains concatenation and scope resolution is also going to give me a simple treatment on the == and === operators in this weakly typed language. PHP is not an elegant language and given the choice, I'd nearly always prefer to be writing something else. But I took my time to respond to this because there's enough wrong with PHP that we don't need to resort to hyperbole to bash it.
- prodigal_erik 17y agoI mostly agree, except that I don't think any treatment explaining NULL != "0" == false == NULL == 0 == "false" == true is going to be simple.
- encoderer 17y agoSure it is: To avoid implicit type coercion, use the identity operators === and !==. Of course, the code you posted doesn't parse without adding parens. And when you do, it becomes much more obvious what it's doing and why.
- prodigal_erik 17y agoSorry, I meant that as a bunch of compares that are mutually inconsistent, not one big expression. And "don't use ==" isn't really a solution until you persuade the runtime and every major library author to stop using it.
- encoderer 17y agoI don't get your point. Nobody has said "don't use equality." Equality is the right choice nearly all the time. I've worked on some very large web apps (mostly C#, Python and PHP) and I can't recall ever really being foiled by php's implicit casting. Just out of genuine curiousity, can you share an example where this caused a problem that you had to debug? And if php implicit casting did somehow cause you problems, surely it was fixed by changing it from equality to identity? So in summary... this could potentially cause a bug, but probably not, and if it does, it would be a consistent bug, and it would be fixed by a single keystroke. Why, again, are we talking about this?
- ars 17y agoThat isn't legal PHP.
- ars 17y ago== is not the equality operator. === is the equality operator. == is the type coerce/cast and then compare operator. I agree with you about the way strings get converted to int instead of the other way around. I believe this is a backwards compatibility issue, and if they could change it they would, but it's too late. It's also because of 1 == "01" would be false otherwise. And if you think "01" is strange you forget that all input to a php program comes from web forms, and is always a string.
- catch23 17y agoin javascript: 1 == '01' --> true 0 == 'x' --> false 1 == '1' --> true true == 'asdf' --> false '-2' == 2 --> true '-2' == 0 --> false Seems like in javascript, the coercing is much more sane. In php, all of the above statements would end up true.
- encoderer 17y agoI don't have a PHP runtime in front of me, but IIRC the first one on your list and the last 2 will evaluate false in php
- ars 17y agoJavascript is not totally sane: '\t\r\n' == 0 --> true And not transitive: "false" == "0" --> false "0" == 0 --> true 0 == false --> true false == "false" --> false It's basically impossible to make a loosely typed equality perfect. PHP is much more strict about the rules used when doing the comparison, javascript is more loose. It tries to guess. When comparing a string to a number, if the string looks like a number it's converted to one. But if it doesn't, then instead the number get converted to a string. This works well most of the time - but not always, since it can surprise you. PHP is more strict, so it doesn't work as often, but it fails more consistently, so it's easier to find the problem. Another example: "1" == "01" --> false "01" == 1 --> true 1 == "1" --> true
- BerislavLopac 17y agoThe funny thing is that in Javascript: 12 == parseInt('012') returns false. :)
- deleted 17y ago[deleted]
- apgwoz 17y agoMaybe I shouldn't, but I find it sort of maddening that, PHP WTF would be powered by software written in PHP. I mean, if it bothers this guy to the extreme that he would go register a domain, and put up a website about it, it shouldn't be much trouble to learn a brand spanking new programming language that doesn't have all the problems he's discussing, right? PHP has many problems. We know this. There are millions of words online that will attest to this fact. The fact is, all these words are for naught if people don't step in and do something about it.
- edw519 17y agoAnyone squatting on PHPWhining.com?
- apgwoz 17y agoAs a matter of fact, it looks like it is currently available. feel free to register it and collect all your favorite links to websites complaining about PHP!
- idlewords 17y agoPeople who make heavy use of a language are in a good position to vent about its shortcomings. Sometimes a language is the best tool for the job despite its many deficiencies, and I'd much rather read these kind of rants by someone who knows the language inside out. I hate PHP more than I hate my own mother, and yet I still chose it for my most recent project. Every programming language has shortcomings, it's just a question of picking the best shortcomings for the job.
- bdotdub 17y agoYeah, he even has some sort of disclaimer in his footer This site is mostly written by chx, one of the core developers of the PHP-based Drupal project. It's not meant to be a bashing of PHP or its authors.
- randallsquared 17y agoI hate PHP more than I hate my own mother I've heard of damning with faint praise, but this is more like faint condemnation...
- Deestan 17y agoSo: 0 == 'x' results in bool(true) Does anyone know the technical reasons for this?
- rbanffy 17y agodaeken explained it quite well. From his post: "As explained under 'read more', it's because 'test' will be cast to a number for comparison. Since 'test' isn't a number, it becomes 0, which is equivalent."
- mlLK 17y agoThese tables illustrate how complicated type checking in PHP really is: http://www.php.net/manual/en/types.comparisons.php http://www.php.net/manual/en/types.comparisons.php
- niyazpk 17y ago"Posted Every Day" ? I could only find 2 posts in the website. Wake me up when it has at least a dozen articles.
- Pistos2 17y agoAgreed; it might have been better marketing to have at least 6 posts up before announcing the site.
- erikwiffin 17y agoYou need a submission form. or not... there's no way you could sort through all the submissions you'd get. If you can keep it from devolving into thedailywtf.com then you'll have a very loyal reader in me. I work in PHP and I would love to hear a list of valid frustrations instead of the general PHP bashing.
- TallGuyShort 17y agoDid anyone read this disclaimer at the bottom of the page? "It's not meant to be a bashing of PHP or its authors." And if so, does anyone understand how that site isn't mean to be a bashing of PHP? I mean, he's free to bash it if he wants, but does that even make sense?
- RossM 17y agoYes. While it seems to be the trend to bash on PHP there's nothing wrong with discussing it's shortcomings in a constructive manner.
- bemmu 17y agoIf you want the strict non-coerced equality, I think you are supposed to use === as in javascript.
- lsb 17y agoThat's like shooting fish in a barrel.
- AlphaEvolve 17y agoplease someone create aspwtf
- j_baker 17y agoWhile we're doing outdated technologies, can we also do a COBOL wtf?
- AlphaEvolve 17y agoif ($countarticles == '2') { postponeLaunch($credibility); }
- Jem 17y agoNo need for the '' around 2 ;)
- deleted 17y ago[deleted]
- LogicHoleFlaw 17y agoIt's PHP, it works anyway.
- xtho 17y agoIf they ever make it to posting #3, there is a chance this site will outlive php.
- petercooper 17y agoUnlike many blogs, at least this one will easily have enough material to keep going for several years.. ;-)