Php what does .= do

Note that even though PHP borrows large portions of its syntax from C, the ',' is treated quite differently. It's not possible to create combined expressions in PHP using the comma-operator that C has, except in for loops. Note that there is a difference between a function and a function call, and both are expressions.

PHP has two kinds of function, "named functions" and "anonymous functions". Its name is "double". A "function call" is an expression with the value of whatever the function returns. Notice that named functions are more awkward than anonymous functions. PHP treats them differently because it didn't use to have anonymous functions, and the way named functions were implemented didn't work for anonymous functions when they were eventually added.

This means that instead of using a named function literally, like we can with anonymous functions, we have to use a string containing its name instead. PHP makes sure that these strings will be treated as functions when it's appropriate. This makes code like "'double' 5 " invalid, so we have to do tricks like using temporary variables.

Passing functions around as expressions like this is very useful whenever we need to use a 'callback'. A note about the short-circuit behaviour of the boolean operators. The reason for this behaviour comes probably from the programming language C, on which PHP seems to be based on. There the short-circuiting can be a very useful tool. This is important, because if you try to access an array whose address is invalid, the program will crash and die a horrible death. The short-circuiting IS a feature.

Post- operations operate on a variable after it has been 'checked', but it doesn't necessarily state that it should happen AFTER an evaluation is over on the contrary, as a matter of fact. An easy fix although intuitively tough to do I know this isn't strictly PHP, but what about including a link to phpdoc.

Can I suggest square bracket and curly bracket? I ran into this problem a lot too not being able to search for special characters , which is why I made SymbolHound , a search engine that doesn't ignore special characters.

I also posted it on StackApps. Well, from the heading Why is this? A question was asked today Nov. I believe that should be amended somewhere. Show 12 more comments. Active Oldest Votes. These can go before or after the variable. I just ate one. Stack Overflow Posts: Understanding Incrementing.

Improve this answer. For everyone's sake, please remove the bolded information about pre-incrementing being infinitesimally faster. This is the absolute worst example of premature optimization and this kind of information should not be in people's heads if they are just starting to learn PHP. Lotus - I consider it a fun fact. I found it fascinating. Peter Ajtai Yes, it's interesting, but from the way you've structured your post you make it seem like one of the prime facts of PHP that is absolutely vital to using the language.

Add a comment. Bitwise Operator What is a bit? A bit is a representation of 1 or 0. Well let's see using our table example. The operator results in an integer expression of: 0 when both operands are equal Less than 0 when the left-hand operand is less than the right-hand operand Greater than 0 when the left-hand operand is greater than the right-hand operand e. Before PHP 7 you would write It doesn't work for non-integer numbers, because usort casts your comparator function's return values to int , which means 0.

MarkAmery the migration guide isn't the documented behavior of the operator. For that you want to look at the language operators section of the manual for that php. Sure, it's almost always 1, 0, or -1, but for the cases where you can't guarantee it like in wrapping libc's strcmp, you offer up the same defined behavior as the underlying spec to be safe — Sherif. MarkAmery The point here is not to allow people to rely on undefined behavior.

For the one case where someones gets a value that is not exactly 1, 0, or -1, you get someone filing a bug report thinking there's something wrong in the language. Which is why we document that all we can guarantee is that value will be less than , greater than , or equal to 0, and not necessarily 1, 0, and Show 6 more comments. Any idea what the double underscore function is?

It is used in WordPress. I cannot find a definition for it anywhere. Example of its use: core. SherylHohman Look like it is translation function. Thanks so much! I envy your superior Google skills and vast coding knowledge :- — SherylHohman. Type Operators instanceof is used to determine whether a PHP variable is an instantiated object of a certain class. The above works with 'interfaces' as well. This is useful for checking that a particular interface is available.

Available as of PHP 7. Maybe it can be used in other cases too. Null coalescing operator?? Rizier : What does mean by "Heredocs can not be used for initializing class properties. The second section translates a simple string from English to Brazilian Portuguese, and the third does the same, but leveraging string replacement from sprintf so the translation may contain the user name and visit date. The last section is a sample of pluralization forms, displaying the singular and plural version as msgid in English and their corresponding translations as msgstr 0 and 1 following the number given by the plural rule.

The plural forms always have two msgid singular and plural , so it is advised not to use a complex language as the source of translation.

As you might have noticed, we are using as source ID the actual sentence in English. That msgid is the same used throughout all your. The Gettext manual favors the first approach as, in general, it is easier for translators and users in case of trouble. That is how we will be working here as well. However, the Symfony documentation favors keyword-based translation, to allow for independent changes of all translations without affecting templates as well. In a typical application, you would use some Gettext functions while writing static text in your pages.

Those sentences would then appear in. One of the great advantages Gettext has over custom framework i18n packages is its extensive and powerful file format. This guide is based on PoEdit 1. Now, save the file - using that directory structure we mentioned as well. After setting those points it will run a scan through your source files to find all the localization calls. After every scan PoEdit will display a summary of what was found and what was removed from the source files.

Save it and a. As you may have noticed before, there are two main types of localized strings: simple ones and those with plural forms. The first ones have simply two boxes: source and localized string. Tip: you may right-click a translation line and it will hint you with the source files and lines where that string is being used. On the other hand, plural form strings include two boxes to show the two source strings, and tabs so you can configure the different final forms. Whenever you change your sources and need to update the translations, just hit Refresh and Poedit will rescan the code, removing non-existent entries, merging the ones that changed and adding new ones.

It may also try to guess some translations, based on other ones you did. It is also useful if you have a translation team and someone tries to write something they are not sure about: just mark Fuzzy, and someone else will review later. From that menu, you can also open parts of the UI that allow you to leave contextual information for translators if needed. It happens the first time it is read, and then, to update it, you might need to restart the server.

Many custom i18n libraries from frameworks use something similar to t as well, to make translated code shorter. However, that is the only function that sports a shortcut. It is just a field in the.

You need to include there the specifications of those new functions, following a specific format :. After including those new rules in the. Dependency injection is a software design pattern that allows the removal of hard-coded dependencies and makes it possible to change them, whether at run-time or compile-time.

This quote makes the concept sound much more complicated than it actually is. Dependency Injection is providing a component with its dependencies either through constructor injection, method calls or the setting of properties.

It is that simple. Here we have a Database class that requires an adapter to speak to the database. We instantiate the adapter in the constructor and create a hard dependency. This makes testing difficult and means the Database class is very tightly coupled to the adapter.

Now we are giving the Database class its dependency rather than creating it itself. These are the complex problems that Dependency Injection solves. In terms of Dependency Injection, this means loosening our dependencies by controlling and instantiating them elsewhere in the system.

For years, PHP frameworks have been achieving Inversion of Control, however, the question became, which part of control are we inverting, and where to? For example, MVC frameworks would generally provide a super object or base controller that other controllers must extend to gain access to its dependencies.

This is Inversion of Control, however, instead of loosening dependencies, this method simply moved them. Dependency Injection allows us to more elegantly solve this problem by only injecting the dependencies we need, when we need them, without the need for any hard coded dependencies at all.

The Single Responsibility Principle is about actors and high-level architecture. The largest benefit of this approach is that it enables improved code reusability. By designing our class to do just one thing, we can use or re-use it in any other program without changing it. Practically speaking, this means that we should write classes that implement and adhere to interfaces , then type-hint against those interfaces instead of specific classes.

The largest benefit of this approach is that we can very easily extend our code with support for something new without having to modify existing code, meaning that we can reduce QA time, and the risk for negative impact to the application is substantially reduced. We can deploy new code, faster, and with more confidence. The Liskov Substitution Principle is about subtyping and inheritance.

For example, if we have a FileInterface interface which defines an embed method, and we have Audio and Video classes which both implement the FileInterface interface, then we can expect that the usage of the embed method will always do the thing that we intend. If we later create a PDF class or a Gist class which implement the FileInterface interface, we will already know and understand what the embed method will do.

The largest benefit of this approach is that we have the ability to build flexible and easily-configurable programs, because when we change one object of a type e.

For example, a Car or Bus class would be interested in a steeringWheel method, but a Motorcycle or Tricycle class would not. Conversely, a Motorcycle or Tricycle class would be interested in a handlebars method, but a Car or Bus class would not. There is no need to have all of these types of vehicles implement support for both steeringWheel as well as handlebars , so we should break-apart the source interface. The Dependency Inversion Principle is about removing hard-links between discrete classes so that new functionality can be leveraged by passing a different class.

Do not depend on concretions. We can easily refactor the above example to follow this principle. There are several benefits to the Database class now depending on an interface rather than a concretion. Consider that we are working in a team and the adapter is being worked on by a colleague. In our first example, we would have to wait for said colleague to finish the adapter before we could properly mock it for our unit tests. An even bigger benefit to this method is that our code is now much more scalable.

If a year down the line we decide that we want to migrate to a different type of database, we can write an adapter that implements the original interface and injects that instead, no more refactoring would be required as we can ensure that the adapter follows the contract set by the interface. The first thing you should understand about Dependency Injection Containers is that they are not the same thing as Dependency Injection.

A container is a convenience utility that helps us implement Dependency Injection, however, they can be and often are misused to implement an anti-pattern, Service Location. Injecting a DI container as a Service Locator in to your classes arguably creates a harder dependency on the container than the dependency you are replacing.

It also makes your code much less transparent and ultimately harder to test. Most modern frameworks have their own Dependency Injection Container that allows you to wire your dependencies together through configuration. What this means in practice is that you can write application code that is as clean and de- coupled as the framework it is built on. Many times your PHP code will use a database to persist information. You have a few options to connect and interact with your database.

The recommended option until PHP 5. Native drivers are great if you are only using one database in your application, but if, for example, you are using MySQL and a little bit of MSSQL, or you need to connect to an Oracle database, then you will not be able to use the same drivers. The mysql extension for PHP is incredibly old and has been superseded by two other extensions:.

Not only did development stop long ago on mysql , but it was deprecated as of PHP 5. To save digging into your php. Even if you are not using PHP 7. Not only is that a gross oversimplification, it misses out on the advantages that mysqli provides, such as parameter binding, which is also offered in PDO. More importantly, PDO allows you to safely inject foreign input e. This is possible using PDO statements and bound parameters. This ID should be used to fetch a user record from a database.

This is the wrong way to do this:. This is terrible code. You are inserting a raw query parameter into a SQL query. This will get you hacked in a heartbeat, using a practice called SQL Injection. This is correct code. It uses a bound parameter on a PDO statement. This escapes the foreign input ID before it is introduced to the database preventing potential SQL injection attacks.

You should also be aware that database connections use up resources and it was not unheard-of to have resources exhausted if connections were not implicitly closed, however this was more common in other languages. Using PDO you can implicitly close the connection by destroying the object by ensuring all remaining references to it are deleted, i. When developers first start to learn PHP, they often end up mixing their database interaction up with their presentation logic, using code that might look like this:.

While there are many other solutions to doing this - depending on if you prefer OOP or functional programming - there must be some element of separation. That is a good start. Create a simple. This is essentially the same as what most modern frameworks are doing, albeit a little more manual. You might not need to do all of that every time, but mixing together too much presentation logic and database interaction can be a real problem if you ever want to unit-test your application.

Many frameworks provide their own abstraction layer which may or may not sit on top of PDO. These will often emulate features for one database system that is missing from another by wrapping your queries in PHP methods, giving you actual database abstraction instead of just the connection abstraction that PDO provides. This will of course add a little overhead, but if you are building a portable application that needs to work with MySQL, PostgreSQL and SQLite then a little overhead will be worth it for the sake of code cleanliness.

Some abstraction layers have been built using the PSR-0 or PSR-4 namespace standards so can be installed in any application you like:. Templates provide a convenient way of separating your controller and domain logic from your presentation logic. The main benefit to using templates is the clear separation they create between the presentation logic and the rest of your application. Templates have the sole responsibility of displaying formatted content.

They are not responsible for data lookup, persistence or other more complex tasks. This leads to cleaner, more readable code which is especially helpful in a team environment where developers work on the server-side code controllers, models and designers work on the client-side code markup. Templates also improve the organization of presentation code. This approach encourages code reuse where larger blocks of code are broken into smaller, reusable pieces, often called partials.

For example, your site header and footer can each be defined as templates, which are then included before and after each page template. Finally, depending on the library you use, templates can offer more security by automatically escaping user-generated content. Some libraries even offer sand-boxing, where template designers are only given access to white-listed variables and functions. They are a natural choice since PHP is actually a template language itself. This is beneficial to PHP developers as there is no new syntax to learn, they know the functions available to them, and their code editors already have PHP syntax highlighting and auto-completion built-in.

Further, plain PHP templates tend to be very fast as no compiling stage is required. Outside of frameworks, libraries like Plates or Aura. View make working with plain PHP templates easier by offering modern template functionality such as inheritance, layouts and extensions.

From automatic escaping, to inheritance and simplified control structures, compiled templates are designed to be easier to write, cleaner to read and safer to use. Compiled templates can even be shared across different languages, Mustache being a good example of this. Since these templates must be compiled there is a slight performance hit, however this is very minimal when proper caching is used.

While it does have exceptions and more of the core is starting to use them when working with objects, most of PHP itself will try to keep processing regardless of what happens, unless a fatal error occurs. This is only a notice error, and PHP will happily carry on.

The only real difference is that Python will freak out over any small thing, so that developers can be super sure any potential issue or edge-case is caught, whereas PHP will keep on processing unless something extreme happens, at which point it will throw an error and report it. PHP has several levels of error severity. The three most common types of messages are errors, notices and warnings. Notices are advisory messages caused by code that may or may not cause problems during the execution of the script, execution is not halted.

Warnings are non-fatal errors, execution of the script will not be halted. These messages are used to suggest changes to your code to help ensure best interoperability and forward compatibility with upcoming versions of PHP. You can also control whether or not errors are displayed to the screen good for development or hidden, and logged good for production.

For more information on this check out the Error Reporting section. Projects have to consider backwards-compatibility issues when upgrading and make the changes at the right time, so it is assumed most projects will eventually adopt, but it is not a requirement.

If you think that your project would benefit from implementing PSRs and you want to have a say in the development of future standards then you certainly should get involved. Multiple members can represent a single project, but that project will only get one vote. A member can represent multiple projects, but that member will still only get one vote. The rules are all described in the Voting Protocol Bylaws.

Every single vote has a number of reasons for and against voting. No explicit guideline or explicit set of rules has been set out.

Some vote for everyone, some vote for their friends, some vote for projects with a certain size or reputation. If a project you use is not represented they have either not applied, or were not involved enough in discussion prior to submitting their vote that they have not been voted in. They can try again at a later date, of course. It was quickly discovered that CMS, applications, package developers, etc.